Торта

using System;
using System.Diagnostics.Tracing;

namespace КоледнаШапка
{
    class Program
    {
        static void Main(string[] args)
        {
            var w = int.Parse(Console.ReadLine());
            var l = int.Parse(Console.ReadLine());

            var pieces = w * l;
            var piecesCount = 0;

            for (int i = 1; i <= 1000; i++)
            {
                try
                {
                    var piecesEat = int.Parse(Console.ReadLine());

                    piecesCount = piecesCount + piecesEat;
                }
                catch
                {
                    break;
                }
            }
            var diff = pieces - piecesCount;

            if (diff >= 0)
            {
                Console.WriteLine($"{diff} pieces are left.");
            }
            else
            {
                diff = Math.Abs(diff);
                Console.WriteLine($"No more cake left! You need {diff} pieces more.");
            }
        }
    }
}