void setup() {
  // put your setup code here, to run once:
  pinMode(7, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(5, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  for(int i=5;i<8;i++)
  {
    digitalWrite(i, HIGH);
    delay(500); // Wait for 1000 millisecond(s)
    digitalWrite(i, LOW);
    delay(500); // Wait for 1000 millisecond(s)
  }
}