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

uint8_t x = 0X00;
uint8_t flag;
ISR(PCINT2_vect)
{
  if (PINK&=~(1<<3)) {
    flag = 1 ;
  }
  if (PINK&=~(1<<4)) {
    flag = 2 ;
  }
}
int main (void)
{
  DDRA |= 0XFF;
  DDRK &= ~(1 << 0);
  DDRK &= ~(1 << 1);
  PORTK |= (1 << 3);
  PORTK |= (1 << 4);
  PCMSK2 |= (1 << PCINT19) | (1 << PCINT20);
  PCICR |= _BV(PCIE2);
  sei();
  while (1) {
    switch (flag) {
      case 0:
        PORTA = 0X00;
        sei();
        break;
      case 1:
        x++;
        PORTA = x;
        _delay_ms(500);
        sei();
        break;
      case 2:
        x--;
        PORTA = x;
        _delay_ms(500);
        sei();
        break;
    }
  }
}