#include <bits/stdc++.h>

using namespace std;

template<typename T> inline T gcd(T a, T b) {
  return __gcd(a, b);
}

template<typename T> inline T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}

template<typename T> inline T floor(T a, T b) {
  return floor(a / b) * b <= a ? floor(a / b) : floor(a / b) - 1;
}

template<typename T> inline T ceil(T a, T b) {
  return floor(a + b - 1, b);
}

template<typename T> inline T round(T a, T b) {
  return floor(a + b / 2);
}

template<typename T> inline T mod(T a, T b) {
  return a - floor(a, b) * b;
}

template<typename T> inline T factorial(T n) {
  return n <= 1 ? 1 : factorial(n - 1) * n;
}

int main() {
  int a, b, t;
  cin >> a >> b >> t;
  int aa = 0, bb = ceil(t, b), res = bb * b;
  for (int i = 0; i < a && bb; ++i) {
    --bb;
    aa = ceil(t - bb * b, a);
    res = min(res, aa * a + bb * b);
  }
  cout << res << endl;
}