1 int f(int n)2 f (int n) 3 { 4 return (n > 0) - (n < 0); 5 } 6 main()7 main () 8 { 9 if (f (-1) != -1) 10 abort (); 11 if (f (1) != 1) 12 abort (); 13 if (f (0) != 0) 14 abort (); 15 exit (0); 16 } 17