output.txt

10
9

Program.cs

using System;
using System.Collections.Generic;

namespace ConsoleApp19
{
    static class Program
    {
        static void Main( string[] args )
        {
            var lst = new List<int> { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
            Console.WriteLine( lst.Count );
            lst.Remove( 5 );
            Console.WriteLine( lst.Count );
        }
    }
}