int A=LOW;
void setup()
{
  DDRC &= B000001; 
  DDRB = B010000;
PCICR =B00000010;
   PCMSK1=B00000001;
      sei();
}

void loop()
{
    PORTB &=B010000;
 delay(100); 
}

ISR (PCINT1_vect)
{
 {
  if(PINC & B000001 &!A)
  
  PORTB ^= B010000;
}
}