const int pinRed = 12;
const int pinYellow = 11;
const int pinGreen = 10;
const int ButtonRed = 8;
const int ButtonYellow = 7;
const int ButtonGreen = 6;
void setup() {
  pinMode(pinRed, OUTPUT);
  pinMode(ButtonRed,INPUT_PULLUP);
  pinMode(pinYellow, OUTPUT);
  pinMode(ButtonYellow, INPUT_PULLUP);
  pinMode(pinGreen, OUTPUT);
  pinMode(ButtonGreen, INPUT_PULLUP);

}

void loop() {
  if(digitalRead(ButtonRed)==LOW){
    if (digitalRead(pinRed)==LOW){
    digitalWrite(pinYellow, LOW);
    digitalWrite(pinGreen, LOW);
    digitalWrite(pinRed,HIGH);
    delay(100);
    } else{
    digitalWrite(pinYellow, LOW);
    digitalWrite(pinGreen, LOW);
    digitalWrite(pinRed,LOW);
    delay(100);
    }
  }
  else if(digitalRead(ButtonYellow)==LOW){
    if (digitalRead(pinYellow)==LOW){
    digitalWrite(pinGreen, LOW);
    digitalWrite(pinRed, LOW);
    digitalWrite(pinYellow,HIGH);
    delay(100);
    } else{
    digitalWrite(pinGreen, LOW);
    digitalWrite(pinRed, LOW);
    digitalWrite(pinYellow,LOW);
    delay(100);
    }
  }
  if(digitalRead(ButtonGreen)==LOW){
    if (digitalRead(pinGreen)==LOW){
    digitalWrite(pinGreen, HIGH);
    digitalWrite(pinRed, LOW);
    digitalWrite(pinYellow,LOW);
    delay(100);
    } else{
    digitalWrite(pinGreen, LOW);
    digitalWrite(pinRed, LOW);
    digitalWrite(pinYellow,LOW);
    delay(100);
    }
  }

}