#include<iostream>

int main(){
    long long a, b, c;
    std::cin >> a >> b >> c;

    long long l = 0;
    long long r = 1e18;

    while(r - l > 1){
        long long mid = (l + r) / 2;
        long long year = mid / a;
        long long money = mid + year * b - year;

        if(money >= c) r = mid;
        else l = mid;
        std::cerr << l << " " << r  << std::endl;
    }

    std::cout << r << std::endl;

}