int LED_R = 2;
int LED_Y = 21;
int LED_G = 22;
void setup() {
  pinMode(LED_R,OUTPUT);
  pinMode(LED_Y,OUTPUT);
  pinMode(LED_G,OUTPUT);
}
void loop(){
  digitalWrite(LED_R, HIGH);
  delay(5000);
  digitalWrite(LED_R, LOW);
  delay(1000);
  digitalWrite(LED_Y, HIGH);
  delay(5000);
  digitalWrite(LED_Y, LOW);
  delay(1000);
  digitalWrite(LED_G, HIGH);
  delay(5000);
  digitalWrite(LED_G, LOW);
  delay(1000);
}