백준 C# - 2501

using System;
using System.Collections.Generic;

namespace baek2
{  
    class Program
    {        
        static void Main(string[] args)
        {
            string n_string = Console.ReadLine();
            string[] token = n_string.Split();

            int n = int.Parse(token[0]);
            int k = int.Parse(token[1]);
            int a = n;
            List<int> pig = new List<int>();

            while (a > 0)
            {
                if (n % a == 0)
                {
                    pig.Add(a);
                }
                a--;
            }
            pig.Sort();

            if (pig.Count < k) Console.WriteLine(0);
            else Console.WriteLine(pig[k-1]);
        }
    }
}