A Math Problem

    1#include <bits/stdc++.h>
    2using namespace std;
    3int main(){
    4    ios::sync_with_stdio(0); cin.tie(0);
    5    int k, p, x; cin >> k >> p >> x;
    6    double pre = x * 1 + (k * p) / 1;
    7    for(double i = 2; ; i++){
    8        double f = x * i + (k * p) / i;
    9        if(f > pre) break;
    10        pre = f;
    11    }
    12    cout << fixed << setprecision(3) << pre << '\n';
    13    return 0;
    14}