output_description: When the minimum required number of recorders is x, print the value of x.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N C
      s_1 t_1 c_1
      :
      s_N t_N c_N
attempt: from operator import attrgetter
  
  
  class Data:
      def __init__(self, s, t, c):
          self.s = s
          self.t = t
          self.c = c
  
  
  N, C = map(int, input().split())
  data_list = []
  for _ in range(N):
      s, t, c = map(int, input().split())
      data_list.append(Data(s, t, c))
  
  ch_map = {}
  for data in data_list:
      if data.c in ch_map:
          ch_map[data.c].append(data)
      else:
          ch_map[data.c] = [data]
  data_list = []
  
  m = {}
  for key, val in ch_map.items():
      ch_list = sorted(val, key=attrgetter("s"))
      # m = {}
      ch_m = {}
      end = 0
      for ch in ch_list:
          if end <= ch.s:
              for i in range(ch.s - 1, ch.t):
                  if i in m:
                      if i not in ch_m:
                          m[i] += 1
                  else:
                      m[i] = 1
                  ch_m[i] = 1
                  # m[i] = 1
              end = ch.t
          elif end > ch.t:
              for i in range((end + 1, ch.t)):
                  if i in m:
                      if i not in ch_m:
                          m[i] += 1
                  else:
                      m[i] = 1
                  ch_m[i] = 1
                  # m[i] = 1
              end = ch.t
      # ch_map[key] = m
  
  
  max = 0
  for key, val in m.items():
      if max < val:
          max = val
  
  # print(ch_map)
  """
  for i in range(100001):
      cnt = 0
      for key, val in ch_map.items():
          if i in val:
              cnt += 1
      if cnt > max:
          max = cnt
      cnt = 0
  """
  print(max)
  
problem_description: Statement
  
  Joisino is planning to record N TV programs with recorders.
  
  The TV can receive C channels numbered 1 through C.
  
  The i-th program that she wants to record will be broadcast from time s_i to
  time t_i (including time s_i but not t_i) on Channel c_i.
  
  Here, there will never be more than one program that are broadcast on the same
  channel at the same time.
  
  When the recorder is recording a channel from time S to time T (including time
  S but not T), it cannot record other channels from time S-0.5 to time T
  (including time S-0.5 but not T).
  
  Find the minimum number of recorders required to record the channels so that
  all the N programs are completely recorded.
samples: [{"input": "3 2\n    1 7 2\n    7 8 1\n    8 12 1", "output": "2\n    \n\nTwo recorders can record all the programs, for example, as follows:\n\n  * With the first recorder, record Channel 2 from time 1 to time 7. The first program will be recorded. Note that this recorder will be unable to record other channels from time 0.5 to time 7.\n  * With the second recorder, record Channel 1 from time 7 to time 12. The second and third programs will be recorded. Note that this recorder will be unable to record other channels from time 6.5 to time 12.\n\n* * *"}, {"input": "3 4\n    1 3 2\n    3 4 4\n    1 4 3", "output": "3\n    \n\nThere may be a channel where there is no program to record.\n\n* * *"}, {"input": "9 4\n    56 60 4\n    33 37 2\n    89 90 3\n    32 43 1\n    67 68 3\n    49 51 3\n    31 32 3\n    70 71 1\n    11 12 3", "output": "2"}]