int red = 1; 
int blue = 2;
int yellow = 3;


void setup() {
 pinMode(red, OUTPUT);
   pinMode(blue, OUTPUT);
      pinMode(yellow, OUTPUT);


      }

      void loop() {
      digitalWrite(red, HIGH);
      delay(1000);
      digitalWrite(red, LOW);
      digitalWrite(blue, HIGH);
      delay(1000);
      digitalWrite(blue, LOW);
      digitalWrite(yellow, HIGH);
      delay(1000);
      digitalWrite(yellow, LOW);
      }