output_description: If the objective is achievable, print `YES`; if it is unachievable, print
  `NO`.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      S
attempt: # -*- coding: utf-8 -*-
  """
  B - Palindrome-phobia
  https://atcoder.jp/contests/cf17-final/tasks/cf17_final_b
  
  """
  import sys
  
  
  from collections import Counter
  
  
  def solve(S):
      cnt = Counter(S)
      res = sorted([[v, k] for k, v in cnt.items()], reverse=True)
  
      ch = res[0][1]
      prev = None
      cnt[ch] -= 1
      if cnt[ch] == 0:
          del cnt[ch]
  
      d = {"ab": "c", "ac": "b", "ba": "c", "bc": "a", "ca": "b", "cb": "a"}
  
      while cnt:
          if prev is None:
              if len(res) < 2:
                  return "NO"
              else:
                  prev = ch
                  ch = res[1][1]
                  cnt[ch] -= 1
                  if cnt[ch] == 0:
                      del cnt[ch]
          else:
              n_ch = d[prev + ch]
              if cnt[n_ch] > 0:
                  prev, ch = ch, n_ch
                  cnt[n_ch] -= 1
                  if cnt[n_ch] == 0:
                      del cnt[n_ch]
              else:
                  return "NO"
      return "YES"
  
  
  def main(args):
      S = input()
      ans = solve(S)
      print(ans)
  
  
  if __name__ == "__main__":
      main(sys.argv[1:])
  
problem_description: Statement
  
  Snuke has a string S consisting of three kinds of letters: `a`, `b` and `c`.
  
  He has a phobia for palindromes, and wants to permute the characters in S so
  that S will not contain a palindrome of length 2 or more as a substring.
  Determine whether this is possible.
samples: [{"input": "abac", "output": "YES\n    \n\nAs it stands now, S contains a palindrome `aba`, but we can permute the\ncharacters to get `acba`, for example, that does not contain a palindrome of\nlength 2 or more.\n\n* * *"}, {"input": "aba", "output": "NO\n    \n\n* * *"}, {"input": "babacccabab", "output": "YES"}]