1 void foo(int n,int m)2 foo (int n, int m) 3 { 4 if (m == 0) 5 exit (0); 6 else if (n != 0) 7 abort (); 8 else 9 foo (n++, m - 1); 10 } 11 12 int main(void)13 main (void) 14 { 15 foo (0, 4); 16 } 17