int red=2;
int blue=3;
int green=4;


void setup() {
  pinMode(red, OUTPUT);
  pinMode(blue, OUTPUT);
  pinMode(green, OUTPUT);
}

void loop() {
  digitalWrite(red,1);
  delay(1000);
  digitalWrite(red,0);
  digitalWrite(green,1);
  delay(1000);
  digitalWrite(green,0);
  digitalWrite(blue,1);
  delay(1000);
  digitalWrite(blue,0);

}