1main()
2{
3  char c;
4  char d;
5  int nbits;
6  c = -1;
7  for (nbits = 1 ; nbits < 100; nbits++) {
8    d = (1 << nbits) - 1;
9    if (d == c)
10      break;
11  }
12  if (nbits == 100)
13    abort();
14  exit(0);
15}
16