EIUCUBES.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace EIUCUBES
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = NextInt();
            var tmp = 0;
            var count = 0;
            var sum = 0;
            for (int i = 1; i <= n; i++)
            {
                tmp = tmp + i;
                sum += tmp;
                if (sum<=n)
                {
                    count++;
                }
                else
                {
                    break;
                }
            }

            Console.WriteLine(count);
        }


        static int s_index = 0;
        static List<string> s_tokens;

        private static string Next()
        {
            while (s_tokens == null || s_index == s_tokens.Count)
            {
                s_tokens = Console.ReadLine().Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList();
                s_index = 0;
            }
            return s_tokens[s_index++];
        }

        private static bool HasNext()
        {
            while (s_tokens == null || s_index == s_tokens.Count)
            {
                s_tokens = null;
                s_index = 0;
                var nextLine = Console.ReadLine();
                if (nextLine != null)
                {
                    s_tokens = nextLine.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList();
                }
                else
                {
                    return false;
                }

            }
            return s_tokens.Count > 0;
        }

        private static int NextInt()
        {
            return Int32.Parse(Next());
        }

        private static long NextLong()
        {
            return Int64.Parse(Next());
        }
    }
}