#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
using namespace std;

int main(){
    int x, y, z;
    cin >> x >> y >> z;
    double r = (y - z) / double(x - y);
    double d = y - r * x;
    cout << long(round(r * z + d)) << endl;
}