output_description: Print the answer.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N M
      A_1 B_1
      \vdots
      A_M B_M
attempt: n, m = list(map(int, input().rstrip().split(" ")))
  friendships = []
  l = 0
  for mm in range(m):
      a, b = list(map(int, input().rstrip().split(" ")))
      i_a = -1
      i_b = -1
      j_a = -1
      j_b = -1
      for ll in range(l):
          if a in friendships[ll]:
              j_a = friendships[ll].index(a)
              i_a = ll
              break
      for ll in range(l):
          if b in friendships[ll]:
              j_b = friendships[ll].index(b)
              i_b = ll
              break
      if i_a != -1 and i_b != -1:
          if i_a != i_b:
              fb_ls = friendships[i_b]
              for fb in fb_ls:
                  friendships[i_a].append(fb)
                  del friendships[i_b]
                  l -= 1
      elif i_a != -1:
          friendships[i_a].append(b)
      elif i_b != -1:
          friendships[i_b].append(a)
      else:
          l += 1
          friendships.append([a, b])
  print(max([len(friendship) for friendship in friendships]))
  
problem_description: Statement
  
  There are N persons called Person 1 through Person N.
  
  You are given M facts that "Person A_i and Person B_i are friends." The same
  fact may be given multiple times.
  
  If X and Y are friends, and Y and Z are friends, then X and Z are also
  friends. There is no friendship that cannot be derived from the M given facts.
  
  Takahashi the evil wants to divide the N persons into some number of groups so
  that every person has no friend in his/her group.
  
  At least how many groups does he need to make?
samples: [{"input": "5 3\n    1 2\n    3 4\n    5 1", "output": "3\n    \n\nDividing them into three groups such as \\\\{1,3\\\\}, \\\\{2,4\\\\}, and \\\\{5\\\\}\nachieves the goal.\n\n* * *"}, {"input": "4 10\n    1 2\n    2 1\n    1 2\n    2 1\n    1 2\n    1 3\n    1 4\n    2 3\n    2 4\n    3 4", "output": "4\n    \n\n* * *"}, {"input": "10 4\n    3 1\n    4 1\n    5 9\n    2 6", "output": "3"}]