using static System.Math;
using System;

public class Hello
{
    public static long a, b, k;
    static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        a = long.Parse(line[0]);
        b = long.Parse(line[1]);
        k = long.Parse(line[2]);
        getAns();
    }
    static bool check(long t) => t / a + t / b - t / a / b >= k;
    static void getAns()
    {
        if (k == 1) { Console.WriteLine(Min(a, b)); return; }
        if (k == 2) { Console.WriteLine(Max(a, b)); return; }
        var ok = long.MaxValue;
        var ng = 1L;
        while (ok - ng > 1)
        {
            var mid = ng + (ok - ng) / 2L;
            if (check(mid)) ok = mid;
            else ng = mid;
        }
        Console.WriteLine(ok);
    }
}