#define RED 12
#define GRE 2


void setup() {
  // put your setup code here, to run once:
  pinMode(RED, OUTPUT);

  pinMode(GRE, OUTPUT);

}

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

delay(500);
digitalWrite(GRE,HIGH);
digitalWrite(RED,LOW);
delay(500);
}