using System;

using System.Linq;

using System.Collections.Generic;

using System.Collections;

using System.Threading;

using System.Threading.Tasks;

using System.Net;

using System.Net.Http;

​

public class Program

{

    public static void Main()

    {

        var input = "123";

        var list = new List<string> { "*126", "+55 3412345678", "12345678", "87654321", "3498761232" };

        list.Where(s => s.Contains(input))

            .Take(3)

            .Dump();

    }

}