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 = map(int, input().split())
  f = lambda x: int(x) - 1
  l = [[] for _ in range(n)]
  for i in range(m):
      a, b = map(f, input().split())
      l[a].append(b)
      l[b].append(a)
  m = 0
  visit = set()
  for i in range(n):
      if i in visit:
          continue
      queue = [i]
      visit.add(i)
      cnt = 1
      while len(queue) > 0:
          now = queue.pop(0)
          for j in l[now]:
              if j not in visit:
                  visit.add(j)
                  queue.append(j)
                  cnt += 1
      m = max(m, cnt)
  print(m)
  
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"}]