#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 = (0 << PA3);
  //looping
    while (1){
      if (PINA & (1 << PINA3)){
        PORTA = (1 << PA7);
        _delay_ms(500);
      }else {
        PORTA &= ~(1 << PA7);
       _delay_ms(500);
        PORTA;
      }
    }
}