int red(13);
int yellow(8);
int green(2);
int redT(3000);
int yellowT(1000);
int greenT(3000);

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

}

void loop() {

  digitalWrite (green,HIGH);
  digitalWrite (yellow,LOW);
  digitalWrite (red,LOW);
  delay(greenT);

  digitalWrite (yellow,HIGH);
  digitalWrite (red,LOW);
  digitalWrite (green,LOW);
  delay(yellowT);

  digitalWrite (red,HIGH);
  digitalWrite (yellow,LOW);
  digitalWrite (green,LOW);
  delay(redT);
  // put your main code here, to run repeatedly:

}