void setup() 
{
  DDRD   |= 0x08;     //define x0, x1, x2 as OUTPUT
  PORTD   = 0x00;

  DDRB   |= 0x08;     //define LEDs as OUTPUT
  PORTB   = 0x00;

  DDRC  &= ~0x01;     //define Button as INPUT
  PORTC |=  0x01;
}

void loop()
{
  int i = 0;
  while (1)
  {
    if ((PINC & 0x01) == 0x00)                //button pressed?
    {
      i++;
      PORTD = (PORTD & 0xF8) | (i & 0x07);    //delete and set bits
      PORTB = (PORTB & 0xF8) | (i & 0x07);    //delete and set bits
      delay(100); 
    }
  }
}