#include <iostream>
using namespace std;
int main() {
    int a, b, t; cin >> a >> b >> t;
    int y = (t + b-1)/b*b;
    for (int i = 0; i <= t and t < y; i += b) {
        int x = i + (t-i + a-1)/a*a;
        if (x < y) y = x;
    }
    cout << y << endl;
    return 0;
}