extern int __VERIFIER_nondet_int();
void abort() { };
                                                                                                                                                          
                                                                            

/*@ 
    requires (1);
    ensures ((\result < 4));
@*/
int id(int x) {
  if (x==0) return 0;
  int ret = id((unsigned int)x-1) + 1;
  if (ret > 3) return 3;
  return ret;
}

int main() {
  int input = __VERIFIER_nondet_int();
  int result = id(input);
  if (result == 5) {
    ERROR: {/*@ assert(0); */;abort();}
  }
}