using Training20200528.Questions;
using Training20200528.Extensions;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

namespace Training20200528.Questions
{
    /// <summary>
    /// ABC080 D
    /// </summary>
    public class QuestionC : AtCoderQuestionBase
    {
        public override IEnumerable<object> Solve(TextReader inputStream)
        {
            var nc = inputStream.ReadIntArray();
            var totalContents = nc[0];
            var channelCounts = nc[1];
            var contents = Enumerable.Repeat(0, channelCounts).Select(_ => new List<Content>()).ToArray();

            for (int i = 0; i < totalContents; i++)
            {
                var stc = inputStream.ReadIntArray();
                contents[stc[2] - 1].Add(new Content(stc[0], stc[1]));
            }

            var decks = new int[100001];
            foreach (var contentsInChannel in contents)
            {
                contentsInChannel.Sort();
                var lastEnd = -10000;
                foreach (var content in contentsInChannel)
                {
                    if (lastEnd == content.Begin)
                    {
                        decks[content.Begin]++;
                    }
                    else
                    {
                        decks[content.Begin - 1]++;
                    }
                    decks[content.End]--;
                    lastEnd = content.End;
                }
            }

            for (int t = 0; t + 1 < decks.Length; t++)
            {
                decks[t + 1] += decks[t];
            }

            yield return decks.Max();
        }

        struct Content : IComparable<Content>
        {
            public int Begin { get; }
            public int End { get; }

            public Content(int begin, int end)
            {
                Begin = begin;
                End = end;
            }

            public int CompareTo(Content other) => Begin.CompareTo(other.Begin);
        }
    }
}


namespace Training20200528
{
    class Program
    {
        static void Main(string[] args)
        {
            IAtCoderQuestion question = new QuestionC();    // 問題に合わせて書き換え
            var answers = question.Solve(Console.In);
            foreach (var answer in answers)
            {
                Console.WriteLine(answer);
            }
        }
    }
}

#region Base Classes

namespace Training20200528.Questions
{

    public interface IAtCoderQuestion
    {
        IEnumerable<object> Solve(string input);
        IEnumerable<object> Solve(TextReader inputStream);
    }

    public abstract class AtCoderQuestionBase : IAtCoderQuestion
    {
        public IEnumerable<object> Solve(string input)
        {
            var stream = new MemoryStream(Encoding.Unicode.GetBytes(input));
            var reader = new StreamReader(stream, Encoding.Unicode);

            return Solve(reader);
        }

        public abstract IEnumerable<object> Solve(TextReader inputStream);
    }

}

#endregion

#region Extensions

namespace Training20200528.Extensions
{
    internal static class TextReaderExtensions
    {
        internal static int ReadInt(this TextReader reader) => int.Parse(ReadString(reader));
        internal static long ReadLong(this TextReader reader) => long.Parse(ReadString(reader));
        internal static double ReadDouble(this TextReader reader) => double.Parse(ReadString(reader));
        internal static string ReadString(this TextReader reader) => reader.ReadLine();

        internal static int[] ReadIntArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(int.Parse).ToArray();
        internal static long[] ReadLongArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(long.Parse).ToArray();
        internal static double[] ReadDoubleArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(double.Parse).ToArray();
        internal static string[] ReadStringArray(this TextReader reader, char separator = ' ') => reader.ReadLine().Split(separator);
    }
}

#endregion

Measured memory_bytes: 20404