#include <bits/stdc++.h>

#define rep(i, n) for (int (i) = 0; (i) < (int)(n); (i)++)

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
using namespace std;
typedef long long ll;
const ll INF = 1ll<<51;

ll dist[2200];

int main() {
    ll A, B, T;
    cin >> A >> B >> T;
    if (B >= 1000) {
        ll ans = INF;
        for (ll i = 0; i <= 1000000; i++) {
            ll rest = T-i*B;
            if (rest < 0) ans = min(ans, i*B);
            else {ll tmp = rest/A*A+i*B;
                if (tmp < T) tmp += A;
                ans = min(ans, tmp);
            }
        }
        cout << ans << endl;
    } else {
        for (int i = 0; i < 2200; i++) dist[i] = INF;
        for (ll i = 0; i < 2200; i++) {
            ll m = (A*i)%B;
            dist[m] = min(dist[m], i);
        }
        while (1) {
            ll m = T % B;
            if (A*dist[m] <= T) {
                cout << T << endl;
                break;
            }
            T++;
        }
    }
    return 0;
}