const int RED=1;
const int GREEN=2;
const int BLUE=3;
void setup() {
  
// put your setup code here, to run once:
pinMode(RED, OUTPUT);
pinMode(GREEN, OUTPUT);
pinMode(BLUE, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(RED, HIGH);
digitalWrite(GREEN, LOW);
digitalWrite(BLUE, LOW);
delay(500);

digitalWrite(RED, LOW);
digitalWrite(GREEN, HIGH);
digitalWrite(BLUE, LOW);
delay(500);

digitalWrite(RED, LOW);
digitalWrite(GREEN, LOW);
digitalWrite(BLUE, HIGH);
delay(500);
}