const int RedLED=2;
const int YellowLED=3;
const int BlueLED=4;
const int greenLED=5;

void setup() {
  // put your setup code here, to run once:
  pinMode(RedLED, OUTPUT);
  pinMode(YellowLED, OUTPUT);
  pinMode(BlueLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
  
  
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(RedLED, HIGH);
  digitalWrite(YellowLED, HIGH);
  digitalWrite(BlueLED, HIGH);
  digitalWrite(greenLED, HIGH);
  delay(1000);

  digitalWrite(RedLED, LOW);
  digitalWrite(YellowLED, LOW);
  digitalWrite(BlueLED, LOW);
  digitalWrite(greenLED, LOW);
  delay(1000);
}