int ledPin[] = {13, 12, 11,10};
int ledDelay[4]={8000, 4000,2000, 1000};
// declare other required variables
unsigned long currTime;
unsigned long Lastchangetime[4];
int ledstate[4];

void setup() {
  currTime =0;
  for(int i=0;i<4;i++){
    // initialize lastChangeTimes
    ledstate[i] = LOW;
    Lastchangetime[i] = 0;
    pinMode(ledPin[i], OUTPUT);
    digitalWrite(ledPin[i],LOW);
    // set pin mode for ledPins
  }
}


void loop() {
  // implement the toggling logic
  currTime = millis();  // Get current time
  
  for (int i = 0; i < 4; i++) {
    if (currTime - Lastchangetime[i] >= ledDelay[i]) {
      Lastchangetime[i] = currTime;
      ledstate[i] = !ledstate[i];
      digitalWrite(ledPin[i], ledstate[i]);
    }
  }
}