int yellow = 13;
int green = 12;
int red = 11;

int buttonPin = 7;



void setup() {
  pinMode(yellow, OUTPUT);
  pinMode(green, OUTPUT);
  pinMode(red, OUTPUT);

  pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {

int buttonVal = digitalRead(buttonPin);

if (buttonVal == LOW )
{
  digitalWrite(yellow, HIGH);
  digitalWrite(green, HIGH);
  digitalWrite(red, HIGH);
}
else
{
  digitalWrite(yellow, LOW);
  digitalWrite(green, LOW);
  digitalWrite(red, LOW);
}
}