int lamp1=7;
int lamp2=5;
int lamp3=3;

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(lamp1, OUTPUT);
pinMode(lamp2, OUTPUT);
pinMode(lamp3, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(lamp1, HIGH);
digitalWrite(lamp2, LOW);
digitalWrite(lamp3, LOW);
delay(50);
digitalWrite(lamp1, LOW);
digitalWrite(lamp2, HIGH);
digitalWrite(lamp3, LOW);
delay(150);
digitalWrite(lamp1, LOW);
digitalWrite(lamp2, LOW);
digitalWrite(lamp3, HIGH);
delay(200);
}