int L1Red = 19;
int L1Yellow = 18;
int L1Green = 5;
int L2Red = 4;
int L2Yellow = 2;
int L2Green = 15;
byte ledPins[] = {19, 18, 5, 4, 2, 15};
unsigned long cTime = 0;
unsigned long wait = 0;

void setup() {
  pinMode(21, INPUT);
  for (int i = 0; i < 6; i++) // faster way to code the outputs
  {
    pinMode(ledPins[i], OUTPUT);
  }
  attachInterrupt(0,changeLight,RISING);
  digitalWrite(L1Green, HIGH);
  digitalWrite(L2Red, HIGH);

}

void loop() 
{
  digitalWrite(L1Green, LOW);
  digitalWrite(L1Yellow, HIGH);
  delay(5000);
  digitalWrite(L1Yellow,LOW);
  digitalWrite(L1Red,HIGH);
  delay(5000);
  digitalWrite(L2Red,LOW);
  digitalWrite(L2Green, HIGH);
  delay(5000);
  digitalWrite(L2Green, LOW);
  digitalWrite(L2Yellow, HIGH);
  delay(5000);
  digitalWrite(L2Yellow,LOW);
  digitalWrite(L2Red,HIGH);
  delay(5000);
  digitalWrite(L1Red, LOW);
  digitalWrite(L1Green, HIGH);
  delay(5000);

}

void changeLight()
{
  if (digitalRead(L2Green == LOW))
  {
    delay(20000);
    digitalWrite(L1Green, LOW);
    digitalWrite(L1Yellow, HIGH);
    delay(1000000);
    digitalWrite(L1Yellow,LOW);
    digitalWrite(L1Red,HIGH);
    delay(150000);
    digitalWrite(L2Red,LOW);
    digitalWrite(L2Green, HIGH);
    delay(2000000);
    digitalWrite(L2Green, LOW);
    digitalWrite(L2Yellow, HIGH);
    delay(1000000);
    digitalWrite(L2Yellow,LOW);
    digitalWrite(L2Red,HIGH);
    delay(100000);
    digitalWrite(L1Red, LOW);
    digitalWrite(L1Green, HIGH);
    delay(200000);
  }
  
  
}