#define BUTTON_PIN 2
#define LED_PIN 4

int led_state=LOW;

void setup()
{
  pinMode(LED_PIN,OUTPUT); //BIJLI PIN SE LED PE BHEJEGA
  pinMode(BUTTON_PIN, INPUT_PULLUP); //CHECK'S KI BIJLI PIN SE DEVICE PE GYI YA NHI, DEFAULT CASE MEIN HIGH RAKHEGA
}

void loop()
{
  if(digitalRead(BUTTON_PIN)==LOW)
  {
    delay(20);

    if(digitalRead(BUTTON_PIN)==LOW)
    {
      led_state=!led_state;
      digitalWrite(LED_PIN,led_state);

      while(digitalRead(BUTTON_PIN)==LOW)
      {
        ;
      }
    }
  }

}