#include <iostream>
#include <vector>
#include <climits>
#include <algorithm>
using namespace std;
int main() {
	cin.tie(0); ios::sync_with_stdio(false);
	long long A, B, T, sum;
	cin >> A >> B >> T;
	long long ans = LLONG_MAX;
	for (int y = 0; y <= A; y++) {
		sum = B*y + ((T - B*y + A - 1) / A) * A;
		if (sum >= T) {
			ans = min(ans, sum);
		}
		if (B*y >= T) { break; }
	}

	cout << ans << endl;
	return 0;
}