1  f (x)
       2  {
       3    x &= 010000;
       4    x &= 007777;
       5    x ^= 017777;
       6    x &= 017770;
       7    return x;
       8  }
       9  
      10  main ()
      11  {
      12    if (f (-1) != 017770)
      13      abort ();
      14    exit (0);
      15  }