int x = 0;
void setup() {
DDRC &= ~(1<<3);
PORTC |= 1<<3;

DDRC &= ~(1<<2);
PORTC |= 1<<2;

DDRC &= ~(1<<1);
PORTC |= 1<<1;

SREG |= 1<<7; //HLAVNY ISTIC

PCICR |= 1<<PCIE1; //AKTIVUJEM PINOVY RAD DDRC

PCMSK1 |= 1<<PCINT10; //AKTIVUJEME OSOBITNE PIN V DANOM RADE
PCMSK1 |= 1<<PCINT9;
PCMSK1 |= 1<<PCINT11;

DDRD |= 1<<7;
Serial.begin(9600);
}

void loop()
 {
  if(x == 3)
  {
    PORTD |= 1<<7;
    delay(500);
    PORTD &= ~(1<<7);
    delay(500);
  }
    if(x == 2)
  {
    PORTD &= ~(1<<7);
  }
    if(x == 1)
  {
    PORTD |= 1<<7;
  }
  Serial.println(x);
}

ISR(PCINT1_vect) // prerusenie
{
if( (PINC&(1<<2)) == 0)
 {x = 1;}
 if( (PINC&(1<<1)) == 0)
 {x = 2;}
 if( (PINC&(1<<3)) == 0)
  {x = 3;}
  //
}