using static System.Math;
using System;

public class Hello
{
    static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = long.Parse(line[0]);
        var b = long.Parse(line[1]);
        var k = long.Parse(line[2]);
        getAns(a, b, k);
    }
    static void getAns(long a, long b, long k)
    {
        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;
            var chk = mid / a + mid / b - mid / lcm(a, b);
            if (chk >= k) ok = mid;
            else ng = mid;
        }
        Console.WriteLine(ok);
    }
    public static long lcm(long a, long b)
    {
        return a / gcd(a, b) * b;
    }
    static long gcd(long a, long b)
    {
        if (a < b) return gcd(b, a);
        while (b != 0)
        {
            var w = a % b;
            a = b;
            b = w;
        }
        return a;
    }
}