int main() {
  volatile char *dirB, *outB;
  volatile char *dirC, *inC;
  dirB = 0x24; *dirB = 0xff;
  outB = 0x25;
  dirC = 0x27; *dirC = 0x00;
  inC = 0x26;
  while(1) {
    volatile char x;
    x = *inC;
    if((x & 0x04) == 4) {
      *outB = 0xff;
    }
    else 
    {
      *outB = 0x00;
    }
  }
}