int red=2,ye=3,gre=4;
void setup() {
  // put your setup code here, to run once:
pinMode(red,OUTPUT);
pinMode(ye,OUTPUT);
pinMode(gre,OUTPUT);
}
void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(red,1);
delay(3000);
digitalWrite(red,0);
digitalWrite(ye,1);
delay(2000);
digitalWrite(ye,0);
digitalWrite(gre,1);
delay(2000);
digitalWrite(gre,0);
}