#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define llong long long

int main() {
    int b1, b2, b3;
    cin >> b1 >> b2 >> b3;

    llong result = (b3 - b2) * b3 / (b2 - b1) + b1 - (b1*(b3- b2) / (b2 - b1) - (b2 - b1));
    cout << result << "\n";
}