int led_red = 2;
int led_yellow = 3;
int led_green = 4;
int btn_pin = 12;

boolean ledOn = HIGH;

void setup()
{
  pinMode(led_red, OUTPUT);
  pinMode(led_yellow, OUTPUT);
  pinMode(led_green, OUTPUT);
}

void loop()
{
  while (digitalRead(btn_pin)) {
    digitalWrite(led_red, HIGH);
    digitalWrite(led_green, HIGH);
    delay(10);
  }

  digitalWrite(led_yellow, LOW);
  digitalWrite(led_red, HIGH);
  delay(2000);          

  digitalWrite(led_red, LOW);
  digitalWrite(led_green, HIGH);
  delay(2000);          

  digitalWrite(led_green, LOW);
  digitalWrite(led_yellow, HIGH);
  delay(700);
}