#define set0(r,b) r &= ~(1<<b)
#define set1(r,b) r |= 1<<b
#define test(r,b) (r&(1<<b))

int hodnota;
int porovnanie;

void setup() {
  for(int i = 4; i < 8; i++){
    set0(DDRD, i);
    set1(PORTD, i);
  }
  set1(DDRB, 0);
  set0(PORTC, 0);
  set1(SREG, 7);
  set1(PCICR, PCIE2);
  set1(PCMSK2, PCINT23);
  set1(PCMSK2, PCINT22);
  set1(PCMSK2, PCINT21);
  set1(PCMSK2, PCINT20);
  Serial.begin(9600);
}

void loop() {
  hodnota = analogRead(A0);  
  int prevod = map(hodnota, 0, 1023, 1, 5);
  if(prevod > porovnanie){
    Serial.println("Sprava 1");
    set1(PORTB, 0);
  }
  if(prevod < porovnanie){
    Serial.println("Sprava 2");
    set0(PORTB, 0);
  }
}

ISR(PCINT2_vect){
  if(test(PIND, 7) == 0){
    porovnanie = 1;
  }
  if(test(PIND, 6) == 0){
    porovnanie = 2;
  }
  if(test(PIND, 5) == 0){
    porovnanie = 3;
  }
  if(test(PIND, 4) == 0){
    porovnanie = 4;
  }
}