#define RED_A 2
#define YELLOW_A 3
#define GREEN_A 4

#define RED_B 5
#define YELLOW_B 6
#define GREEN_B 7

#define BUTTON_A 8
#define BUTTON_B 9

void setup() {

  pinMode(RED_A, OUTPUT);
  pinMode(YELLOW_A, OUTPUT);
  pinMode(GREEN_A, OUTPUT);

  pinMode(RED_B, OUTPUT);
  pinMode(YELLOW_B, OUTPUT);
  pinMode(GREEN_B, OUTPUT);

  pinMode(BUTTON_A, INPUT);
  pinMode(BUTTON_B, INPUT);

  // start
  digitalWrite(GREEN_A, HIGH);
  digitalWrite(RED_B, HIGH);

}

void loop() {

  // samochód od strony B
  if(digitalRead(BUTTON_B) == HIGH) {

    digitalWrite(GREEN_A, LOW);

    digitalWrite(YELLOW_A, HIGH);
    delay(1000);

    digitalWrite(YELLOW_A, LOW);
    digitalWrite(RED_A, HIGH);

    delay(1000);

    digitalWrite(RED_B, LOW);
    digitalWrite(YELLOW_B, HIGH);

    delay(1000);

    digitalWrite(YELLOW_B, LOW);
    digitalWrite(GREEN_B, HIGH);

  }

  // samochód od strony A
  if(digitalRead(BUTTON_A) == HIGH) {

    digitalWrite(GREEN_B, LOW);

    digitalWrite(YELLOW_B, HIGH);
    delay(1000);

    digitalWrite(YELLOW_B, LOW);
    digitalWrite(RED_B, HIGH);

    delay(1000);

    digitalWrite(RED_A, LOW);
    digitalWrite(YELLOW_A, HIGH);

    delay(1000);

    digitalWrite(YELLOW_A, LOW);
    digitalWrite(GREEN_A, HIGH);

  }

}