diff --git a/conf.pest b/conf.pest
index 3b8810b..cdad2d5 100644
--- a/conf.pest
+++ b/conf.pest
@@ -1,3 +1,5 @@
-world = { ASCII_DIGIT+ ~ " " ~ ASCII_DIGIT+ }
-robot_init = { ASCII_DIGIT+ ~ " " ~ ASCII_DIGIT+ ~ " " ~ ("S" | "N" | "W" | "E") }
-robot_instructions = { ASCII_ALPHA_UPPER+ }
+World = { HeaderWorld ~ NEWLINE+ ~ Robot+ }
+HeaderWorld = { ASCII_DIGIT+ ~ " " ~ ASCII_DIGIT+ }
+Robot = { HeaderRobot ~ NEWLINE ~ Instructions ~ NEWLINE+ }
+HeaderRobot = { ASCII_DIGIT+ ~ " " ~ ASCII_DIGIT+ ~ " " ~ ("S" | "N" | "W" | "E") }
+Instructions = { (("F" | "L" | "R")+) | "" }
diff --git a/src/main.rs b/src/main.rs
index c1bba05..aabe45f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -59,93 +59,91 @@ fn create_hash_map(pool: &Vec<robot::Robot>, hash: &mut HashMap<robot::Position,
     }
 }
 
-/// Generate random instructions.
-fn gen_random_instructions() -> String {
+fn gen_world(pool: &mut Vec<robot::Robot>) -> Result<world::World, String> {
+    let w = world::random_world();
     let mut rng = rand::thread_rng();
-    let n = rng.gen_range(5, 10);
-    let mut instructions = String::with_capacity(n);
-    const CHARSET: &[u8] = b"LRF";
-    for _ in 0..n {
-        let l = rng.gen_range(0, CHARSET.len());
-        instructions.push(CHARSET[l] as char);
+    let x = rng.gen_range(2, 10);
+    for i in 0..=x {
+        let r = robot::Robot::new_random(i + 1, w.x - 2, w.y - 2)?;
+        pool.push(r);
     }
-
-    instructions
+    Ok(w)
 }
 
 /// Parse the config file, generate the world and robot pool.
 fn parse_config(conf: String, pool: &mut Vec<robot::Robot>) -> Result<world::World, String> {
-    let mut lines: Vec<&str> = conf.split('\n').collect();
-    let raw_world = match ConfParser::parse(Rule::world, lines.remove(0)) {
-        Ok(s) => s.as_str(),
-        Err(_) => return Err(String::from("World config is broken.")),
+    let pairs = match ConfParser::parse(Rule::World, &conf) {
+        Ok(p) => p,
+        Err(_) => return Err(String::from("Config is broken.")),
     };
-    let mut w: Vec<i32> = Vec::with_capacity(2);
-    for n in raw_world.split_whitespace() {
-        let v: i32 = n.parse::<i32>().unwrap();
-        w.push(v);
+
+    let mut world = world::World { x: 0, y: 0 };
+    let mut id = 1;
+    for pair in pairs {
+        for inner in pair.into_inner() {
+            match inner.as_rule() {
+                Rule::HeaderWorld => {
+                    let mut w: Vec<i32> = Vec::with_capacity(2);
+                    for n in inner.as_str().split_whitespace() {
+                        let v: i32 = n.parse::<i32>().unwrap();
+                        w.push(v);
+                    }
+                    world = world::World { x: w[0], y: w[1] };
+                }
+                Rule::Robot => {
+                    let mut vpos: Vec<robot::Position> = Vec::new();
+                    let mut vor: Vec<robot::Orientation> = Vec::new();
+                    let mut vinst: Vec<Vec<robot::Instruction>> = Vec::new();
+                    for inner_robot in inner.into_inner() {
+                        match inner_robot.as_rule() {
+                            Rule::HeaderRobot => {
+                                let mut setup = inner_robot.as_str().split_whitespace();
+                                let rx = setup.next().unwrap();
+                                let ry = setup.next().unwrap();
+                                let ro = setup.next().unwrap();
+                                vpos.push(robot::Position {
+                                    x: rx.parse::<i32>().unwrap(),
+                                    y: ry.parse::<i32>().unwrap(),
+                                });
+                                vor.push(match ro {
+                                    "N" => robot::Orientation::N,
+                                    "E" => robot::Orientation::E,
+                                    "S" => robot::Orientation::S,
+                                    _ => robot::Orientation::W,
+                                })
+                            }
+                            Rule::Instructions => {
+                                if !(inner_robot.as_str() == "") {
+                                    let instructions = inner_robot.as_str();
+                                    vinst.push(robot::instructions_from_string(
+                                        instructions.chars().rev().collect::<String>(),
+                                    )?);
+                                } else {
+                                    let instructions = robot::gen_random_instructions();
+                                    vinst.push(robot::instructions_from_string(
+                                        instructions.chars().rev().collect::<String>(),
+                                    )?);
+                                }
+                                let r = robot::Robot::new(
+                                    id,
+                                    vor.pop().unwrap(),
+                                    vpos.pop().unwrap(),
+                                    vinst.pop().unwrap(),
+                                );
+                                match check_map(&r, &world) {
+                                    Ok(()) => pool.push(r),
+                                    Err(err) => return Err(err),
+                                }
+                                id += 1;
+                            }
+                            _ => unreachable!(),
+                        }
+                    }
+                }
+                _ => unreachable!(),
+            };
+        }
     }
-    let world = world::World { x: w[0], y: w[1] };
-    lines.remove(0);
-    let mut r_id: u32 = 0;
-    loop {
-        r_id += 1;
-        if lines.len() == 0 {
-            break;
-        }
-        let raw_setup = match ConfParser::parse(Rule::robot_init, lines.remove(0)) {
-            Ok(s) => s.as_str(),
-            Err(_) => return Err(String::from("Robot setup is broken.")),
-        };
-
-        let rand_instructions = gen_random_instructions();
-        let l = lines.remove(0);
-
-        let instructions = match ConfParser::parse(Rule::robot_instructions, l) {
-            Ok(s) => s.as_str(),
-            Err(_) => rand_instructions.as_str(),
-        };
-
-        let mut setup = raw_setup.split_whitespace();
-        let pos_x = setup.next().unwrap();
-        let pos_y = setup.next().unwrap();
-        let orientation = setup.next().unwrap();
-        // Convert values of the setup line
-        let r_x = pos_x.parse::<i32>().unwrap();
-        let r_y = pos_y.parse::<i32>().unwrap();
-        let r_o = match orientation {
-            "N" => robot::Orientation::N,
-            "E" => robot::Orientation::E,
-            "S" => robot::Orientation::S,
-            "W" => robot::Orientation::W,
-            _ => {
-                return Err(String::from(
-                    "The third token of the setup line do not match any orientations !",
-                ))
-            }
-        };
-        // Convert instructions line.
-        let inst: Vec<char> = instructions.chars().rev().collect();
-        if !robot::is_instructions(&inst) {
-            return Err(String::from("Invalid instructions !"));
-        }
-
-        let r = robot::Robot::new(r_id, r_o, robot::Position { x: r_x, y: r_y }, inst);
-        // Load robot inside the pool.
-        match check_map(&r, &world) {
-            Ok(()) => pool.push(r),
-            Err(err) => return Err(err),
-        }
-
-        if lines.len() == 0 {
-            break;
-        }
-        if l.len() == 0 {
-            continue;
-        }
-        lines.remove(0);
-    }
-
     Ok(world)
 }
 
@@ -213,15 +211,27 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                 .takes_value(false)
                 .help("Generate random world"),
         )
+        .arg(
+            Arg::with_name("random")
+                .short("r")
+                .long("random")
+                .takes_value(false)
+                .help("Generate random world"),
+        )
         .get_matches();
 
-    let raw_conf = open_file(matches.value_of("file").unwrap_or("two_robots.txt"))?;
-
     let mut robot_pool: Vec<robot::Robot> = Vec::new();
-    let mut world: world::World = parse_config(raw_conf, &mut robot_pool)?;
-    world = match matches.is_present("random-world") {
-        false => world,
-        true => world::random_world(),
+    let world = match matches.is_present("random") {
+        true => gen_world(&mut robot_pool)?,
+        false => {
+            let raw_conf = open_file(matches.value_of("file").unwrap_or("two_robots.txt"))?;
+            let mut world: world::World = parse_config(raw_conf, &mut robot_pool)?;
+            world = match matches.is_present("random-world") {
+                false => world,
+                true => world::random_world(),
+            };
+            world
+        }
     };
 
     let mut hash: HashMap<robot::Position, u32> = HashMap::new();
@@ -284,7 +294,7 @@ mod tests {
             0,
             robot::Orientation::N,
             robot::Position { x: 2, y: 3 },
-            vec!['F'],
+            vec![robot::Instruction::F],
         );
         let w = world::World { x: 10, y: 10 };
 
@@ -298,7 +308,7 @@ mod tests {
             0,
             robot::Orientation::N,
             robot::Position { x: 2, y: 4 },
-            vec!['F'],
+            vec![robot::Instruction::F],
         );
         let w = world::World { x: 3, y: 3 };
 
@@ -312,7 +322,7 @@ mod tests {
             0,
             robot::Orientation::N,
             robot::Position { x: 2, y: 3 },
-            vec!['F'],
+            vec![robot::Instruction::F],
         );
 
         let mut h: HashMap<robot::Position, u32> = HashMap::new();
diff --git a/src/robot.rs b/src/robot.rs
index 42e3adc..aa96587 100644
--- a/src/robot.rs
+++ b/src/robot.rs
@@ -9,37 +9,41 @@ pub struct Robot {
     pub id: u32,
     pub o: Orientation,
     pub p: Position,
-    i: Vec<char>,
+    pub i: Vec<Instruction>,
 }
 
 impl Robot {
     /// Create new `Robot` with given id, `Orientation`, `Position` and instructions.
-    pub fn new(id: u32, o: Orientation, p: Position, i: Vec<char>) -> Robot {
+    pub fn new(id: u32, o: Orientation, p: Position, i: Vec<Instruction>) -> Robot {
         Robot { id, o, p, i }
     }
+    /// Create new random `Robot`.
+    pub fn new_random(id: u32, posx_max: i32, posy_max: i32) -> Result<Robot, String> {
+        let mut rng = rand::thread_rng();
+        let x = rng.gen_range(2, posx_max);
+        let y = rng.gen_range(2, posy_max);
+        let inst = gen_random_instructions();
+        let instructions: Vec<Instruction> = instructions_from_string(inst)?;
+        let o: Orientation = rand::random();
+        Ok(Robot {
+            id,
+            o,
+            p: Position { x, y },
+            i: instructions,
+        })
+    }
     /// Apply given instruction to a `Robot`.
     pub fn execute_instruction(&mut self) {
         match self.i.pop() {
             Some(instruction) => match instruction {
-                'L' => match self.o {
-                    Orientation::N => self.o = Orientation::W,
-                    Orientation::E => self.o = Orientation::N,
-                    Orientation::S => self.o = Orientation::E,
-                    Orientation::W => self.o = Orientation::S,
-                },
-                'R' => match self.o {
-                    Orientation::N => self.o = Orientation::E,
-                    Orientation::E => self.o = Orientation::S,
-                    Orientation::S => self.o = Orientation::W,
-                    Orientation::W => self.o = Orientation::N,
-                },
-                'F' => match self.o {
+                Instruction::L => self.o = turn_left(&self.o),
+                Instruction::R => self.o = turn_right(&self.o),
+                Instruction::F => match self.o {
                     Orientation::N => self.p.y += 1,
                     Orientation::E => self.p.x += 1,
                     Orientation::S => self.p.y -= 1,
                     Orientation::W => self.p.x -= 1,
                 },
-                _ => (), // never happens 😉
             },
             None => (),
         }
@@ -55,6 +59,44 @@ pub enum Orientation {
     W,
 }
 
+fn turn_left(o: &Orientation) -> Orientation {
+    match o {
+        Orientation::N => Orientation::W,
+        Orientation::E => Orientation::N,
+        Orientation::S => Orientation::E,
+        Orientation::W => Orientation::S,
+    }
+}
+fn turn_right(o: &Orientation) -> Orientation {
+    match o {
+        Orientation::N => Orientation::E,
+        Orientation::E => Orientation::S,
+        Orientation::S => Orientation::W,
+        Orientation::W => Orientation::N,
+    }
+}
+
+/// Enum to store all possible instructions.
+#[derive(Debug, Eq, PartialEq)]
+pub enum Instruction {
+    L,
+    R,
+    F,
+}
+
+pub fn instructions_from_string(s: String) -> Result<Vec<Instruction>, String> {
+    let mut v: Vec<Instruction> = Vec::new();
+    for c in s.chars() {
+        match c {
+            'L' => v.push(Instruction::L),
+            'R' => v.push(Instruction::R),
+            'F' => v.push(Instruction::F),
+            _ => return Err(String::from("Not an instruction.")),
+        }
+    }
+    Ok(v)
+}
+
 impl Distribution<Orientation> for Standard {
     /// Generating random orientation.
     fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Orientation {
@@ -74,17 +116,18 @@ pub struct Position {
     pub y: i32,
 }
 
-/// Check if instructions list is valid.
-pub fn is_instructions(v: &Vec<char>) -> bool {
-    for c in v {
-        match c {
-            'F' => continue,
-            'R' => continue,
-            'L' => continue,
-            _ => return false,
-        }
+/// Generate random instructions.
+pub fn gen_random_instructions() -> String {
+    let mut rng = rand::thread_rng();
+    let n = rng.gen_range(5, 10);
+    let mut instructions = String::with_capacity(n);
+    const CHARSET: &[u8] = b"LRF";
+    for _ in 0..n {
+        let l = rng.gen_range(0, CHARSET.len());
+        instructions.push(CHARSET[l] as char);
     }
-    true
+
+    instructions
 }
 
 /// Check if a robot is piouff.
@@ -136,13 +179,15 @@ mod tests {
             0,
             Orientation::N,
             Position { x: 1, y: 2 },
-            vec!['L', 'L', 'F', 'R'],
+            vec![Instruction::L, Instruction::F, Instruction::R],
         );
         assert_eq!(r.id, 0);
         assert!(matches!(r.o, Orientation::N));
         assert_eq!(r.p.x, 1);
         assert_eq!(r.p.y, 2);
-        assert_eq!(r.i, vec!['L', 'L', 'F', 'R']);
+        assert_eq!(r.i[0], Instruction::L);
+        assert_eq!(r.i[1], Instruction::F);
+        assert_eq!(r.i[2], Instruction::R);
     }
 
     #[test]
@@ -151,7 +196,12 @@ mod tests {
             0,
             Orientation::N,
             Position { x: 1, y: 2 },
-            vec!['R', 'F', 'L', 'F'],
+            vec![
+                Instruction::R,
+                Instruction::F,
+                Instruction::L,
+                Instruction::F,
+            ],
         );
         let mut hash = std::collections::HashMap::new();
         //hash.insert(&r.p, &r.id); // first insert while initializing.
@@ -166,26 +216,18 @@ mod tests {
         assert_eq!(r.p.y, 3);
     }
 
-    #[test]
-    fn is_instructions_test() {
-        let v = vec!['F', 'R', 'L', 'F'];
-        assert!(is_instructions(&v));
-    }
-
-    #[test]
-    #[should_panic]
-    fn is_instructions_test_fail() {
-        let v = vec!['F', 'R', 'L', 'Z'];
-        assert!(is_instructions(&v));
-    }
-
     #[test]
     fn test_piouf() {
         let mut r: Robot = Robot::new(
             0,
             Orientation::N,
             Position { x: 1, y: 2 },
-            vec!['R', 'F', 'L', 'F'],
+            vec![
+                Instruction::R,
+                Instruction::F,
+                Instruction::L,
+                Instruction::F,
+            ],
         );
         r.i.pop();
         r.i.pop();