#define Line_L 10
#define Line_R 9
#define Sensor 8

#define Motor_L_F 13
#define Motor_L_B 12
#define Motor_R_F 7
#define Motor_R_B 6

void forward(){
  digitalWrite(Motor_L_F, HIGH);
  digitalWrite(Motor_L_B, LOW);
  digitalWrite(Motor_R_F, HIGH);
  digitalWrite(Motor_R_B, LOW);
}

void right(){
  digitalWrite(Motor_L_F, HIGH);
  digitalWrite(Motor_L_B, LOW);
  digitalWrite(Motor_R_F, LOW);
  digitalWrite(Motor_R_B, LOW);
}

void left(){
  digitalWrite(Motor_L_F, LOW);
  digitalWrite(Motor_L_B, LOW);
  digitalWrite(Motor_R_F, HIGH);
  digitalWrite(Motor_R_B, LOW);
}

void stop(){
  digitalWrite(Motor_L_F, LOW);
  digitalWrite(Motor_L_B, LOW);
  digitalWrite(Motor_R_F, LOW);
  digitalWrite(Motor_R_B, LOW);
}

void setup() {
  // put your setup code here, to run once:
  pinMode(Line_L, INPUT);
  pinMode(Line_R, INPUT);
  pinMode(Sensor, INPUT);
  pinMode(Motor_L_F, OUTPUT);
  pinMode(Motor_L_B, OUTPUT);
  pinMode(Motor_R_F, OUTPUT);
  pinMode(Motor_R_B, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(Sensor)==LOW) {
    if (digitalRead(Line_L)==LOW && digitalRead(Line_R)==LOW){
      forward();
    }
    if (digitalRead(Line_L)==HIGH && digitalRead(Line_R)==LOW){
      left();
    }
    if (digitalRead(Line_L)==LOW && digitalRead(Line_R)==HIGH){
      right();
    }
    if (digitalRead(Line_L)==HIGH && digitalRead(Line_R)==HIGH){
      stop();
    }
  } else {
    stop();
  }
}