int main()
{
  volatile char *portb,*ddrb,*portd,*ddrd;
  volatile long i;
  portb=0x25;
  ddrb=0x24;
  *ddrb=0xFF;
  portd=0x29;
  ddrd=0x2A;
  *ddrd=0x00;
  while(1){
    
    if((*portd&0x04)==0x04)
    {
      *portb=0x20;
    }
    else{
      *portb=0x00;
    }
  }
}