using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

        static void Main(string[] args)

        {

            int n = 11;

​

            List<int> factors3 = new List<int>();

            List<int> factors5 = new List<int>();

​

​

            for (var i = 1; i <= n; i++)

            {

                if (i % 3 == 0)

                {

                    factors3.Add(i);

                }

​

                if (i % 5 == 0)

                {

                    factors5.Add(i);

                }

            }

​

            Console.WriteLine(FindNum(factors3, factors5, n));

​

        }

​

        private static string FindNum(List<int> factors3, List<int> factors5, int n)

        {

            foreach (var f3 in factors3)

            {

​

                int f5 = factors5.Where(f => f + f3 == n).SingleOrDefault();

​

                if (f5 != 0 && f3 != 0)

                    return String.Format("5: " + f5 + " | " + "3:" + f3 + "    ");

            }

​

​

​

            if (factors3.Exists(f => f == n))

                factors3.Where()

​

​

            factors5.ForEach(f => Console.WriteLine(f));

​

            Console.ReadLine();

        }

​

}