#define led_pin 3
#define button_pin 2

unsigned long timer;


void setup() {

  pinMode(led_pin, OUTPUT);
  pinMode(button_pin, INPUT);
  Serial.begin(9600);

}

void loop() {
  if (digitalRead(button_pin) == HIGH) {
    timer = millis();
    digitalWrite(led_pin, HIGH);
  }

  if (millis() - timer >= 15000) {

    digitalWrite(led_pin, LOW);

  }

}