void setup() {
  // put your setup code here, to run once:
pinMode(8, OUTPUT);
pinMode(7, OUTPUT);
pinMode(4, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(8,HIGH);
digitalWrite(7,LOW);
delay(1200);
delay(900);
digitalWrite(8, LOW);
digitalWrite(7, HIGH);
delay(1100);
delay(800);
digitalWrite(4, HIGH);
delay(800);
digitalWrite(4, LOW);
delay(700);
}