bool isCircuitOn = false;
bool isSetStartTime = true;

unsigned long startTime = 0;

const int red = 18;
const int green = 19;
const int yellow = 21;
const int on = 2;
const int off = 4;

void setup() {
  pinMode(red, OUTPUT);
  pinMode(green, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(on, INPUT);
  pinMode(off, INPUT);
  digitalWrite(red, LOW);
  digitalWrite(green, LOW);
  digitalWrite(yellow, LOW);
}

void loop() {
  isCircuitOn = digitalRead(on);
  while  (isCircuitOn) {
    if (isSetStartTime) {
      startTime = millis();
      isSetStartTime = false;
    }
    lightSequence();
    if (digitalRead(off)==HIGH) {
      isSetStartTime = true;
      digitalWrite(red, LOW);
      digitalWrite(green, LOW);
      digitalWrite(yellow, LOW);
      break;
    } 
  }
}

void lightSequence() {
  unsigned long currentTime = millis();
  unsigned long interval = currentTime - startTime;
  if (interval == 0) {
    digitalWrite(red, HIGH);
  }
  else if (interval == 250) {
    digitalWrite(red, LOW);
    digitalWrite(green, HIGH);
  }
  else if (interval == 500) {
    digitalWrite(green, LOW);
    digitalWrite(yellow, HIGH);
  }
  else if (interval == 750) {
    digitalWrite(yellow, LOW);
  }
  else if (interval == 1000) {
    isSetStartTime = true;
  }
}