Problem:
Score : 200 points

Problem Statement

You are given positive integers A and B.

Find the K-th largest positive integer that divides both A and B.

The input guarantees that there exists such a number.

Constraints

All values in input are integers.

1 \leq A, B \leq 100

The K-th largest positive integer that divides both A and B exists.

K \geq 1

Input

Input is given from Standard Input in the following format:

A B K

Output

Print the K-th largest positive integer that divides both A and B.

Sample Input 1

8 12 2

Sample Output 1

2

Three positive integers divides both 8 and 12: 1, 2 and 4.
Among them, the second largest is 2.

Sample Input 2

100 50 4

Sample Output 2

5

Sample Input 3

1 1 1

Sample Output 3

1

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AtCoder
{

    class Program
    {
        static void Main(string[] args)
        {
            var vals = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            var A = vals[0];
            var B = vals[1];
            var K = vals[2];

            var divisors = new List<int>();
            for(var i =1; i<=Math.Min(A,B); i++)
            {
                if(A%i==0 && B%i==0)
                {
                    divisors.Add(i);
                }
            }
            Console.WriteLine(divisors.OrderByDescending(x=>x).ToArray()[K - 1]);

        }

    }
}
//B