void setup() {
  // put your setup code here, to run once:
pinMode (6, OUTPUT);
pinMode(5, OUTPUT);
pinMode(4, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(6, HIGH);
digitalWrite(5, LOW);
digitalWrite(4, LOW);
delay(1000);
digitalWrite(6, LOW);
digitalWrite(5, HIGH);
digitalWrite(4, LOW);
delay(1000);
digitalWrite(6, LOW);
digitalWrite(5, LOW);
digitalWrite(4, HIGH);
delay(1000);
}