using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;
using System.IO;

class Program
{
    static void Main()
    {
        new Magatro().Solve();
    }
}

class Magatro
{
    private long B1, B2, B3;

    private void Scan()
    {
        var line = Console.ReadLine().Split(' ');
        B1 = long.Parse(line[0]);
        B2 = long.Parse(line[1]);
        B3 = long.Parse(line[2]);
    }

    public void Solve()
    {
        Scan();
        long ans = (B3 - B2) * (B3 - B1) / (B2 - B1) + B2;
        Console.WriteLine(ans);
    }
}