#include 

using namespace std;

int main()
{
    int p1, p2, p3;
    cin >> p1 >> p2 >> p3;
    int x = p2 - p1;
    if (p1 + x + x == p3)
    {
        cout << p3 + x << endl;
        return 0;
    }
    else
    {
        x = p2 / p1;
        cout << p3 * x << endl;
    }
    return 0;
}