假设输入的所有数都为不超过1000的正整数，完成下面的判断题和单选题:
cpp
1#include <iostream>
2#include <cmath>
3using namespace std;
4,[object Object],
cpp
1int main() {,[object Object],
2cout.flags(ios::fixed);,[object Object],
3cout.precision(4);,[object Object],
4int a, b, c;,[object Object],
5cin >> a >> b >> c;,[object Object],
6cout << f(a, b, c) << endl;,[object Object],
7return 0;,[object Object],
8},[object Object],