int led_R = 8;
int led_G = 9;
int led_Y = 10;
void setup() {
    pinMode((led_R),OUTPUT);
    pinMode((led_G),OUTPUT);
    pinMode((led_Y),OUTPUT);
}

void loop() {
    digitalwrite(led_R,1);
    digitalwrite(led_G,0);
    digitalwrite(led_Y,0);
    delay(1000);

    digitalwrite(led_R,0);
    digitalwrite(led_G,1);
    digitalwrite(led_Y,0);
    delay(1000);

    digitalwrite(led_R,0);
    digitalwrite(led_G,0);
    digitalwrite(led_Y,1);
    delay(1000);
}