#include <avr/io.h>
#include <util/delay.h>

int main (void)
{
//Setting Pin 7 as an OUTPUT.
  DDRA = (1 << PA7);
//Setting Pin 3 as an INPUT.
  DDRA &= ~(1 << PA3);
  //looping
  while (1)
    {
//Setting pin 7(led) to HIGH if you press the button
      PORTA = (1 << PA7);


      _delay_ms(2000);

//Setting pin 7(led) to LOW
      PORTA = (0 << PA7);

      _delay_ms(2000);
    }

  return 1;
}