#include <bits/stdc++.h>
#define rep(i, a) for (int i = 0; i < (a); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) for (int i = (a) - 1; i >= 0; i--)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 7;

int main() {
    ll A, B, T;
    cin >> A >> B >> T;

    if (A < B) swap(A, B);

    ll ans = 1e18;

    for (ll x = 0; x <= B && x * A <= T + A; x++) {
        ll y = (T - A * x + B - 1) / B;

        if (A * x + B * y >= T) {
            ans = min(ans, A * x + B * y);
        }
    }

    cout << ans << endl;
}