ISR (PCINT0_vect)
{
     if (!(PINB & (1<<PINB7))) // if PINB7 is low (Switch pressed)
    {
        PORTB |= (1 <<PORTB5); // Turn ON LED
    }
    else
    {
        PORTB &= ~(1<<PORTB5); // Turn OFF LED
    } 
}        }