int num = 0;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  DDRD &= ~(1<<7);
  PORTD |= (1<<7);
  DDRD &= ~(1<<6);
  PORTD |= (1<<6);
  DDRD &= ~(1<<5);
  PORTD |= (1<<5);
  SREG |= 1<<7;
  PCMSK2 |= 1<<PCINT23;
  PCMSK2 |= 1<<PCINT22;
  PCMSK2 |= 1<<PCINT21;
  PCICR |= 1<<PCIE2;
}

void loop() {
  // put your main code here, to run repeatedly:

}

ISR(PCINT2_vect) //+
  {
    if((PIND&(1<<7)) == 0)
    {
      Serial.println(++num);
    }

    if((PIND&(1<<6)) == 0)
    {
      Serial.println(--num);
    }

        if((PIND&(1<<5)) == 0)
    {
      num = 0;
      Serial.println(num);
    }
  }