using System;

public class Hello
{
    public static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = int.Parse(line[0]);
        var b = int.Parse(line[1]);
        var c = int.Parse(line[2]);
        var r = (c - b) / (b - a);
        var d = c - r * b;
        var ans = ((c - b) * (c - b)) / (b - a) + c;
        Console.WriteLine(ans);
    }
}