new_contents: # Game of thrones
  
  got = input()
  occ_table = {}
  for i in got:
      if i not in occ_table:
          occ_table[i]=1
      else:
          occ_table[i]+=1
  unpaired_chars=0
  for i in occ_table.keys():
      if occ_table[i]%2 is 1:
          unpaired_chars+=1
  if unpaired_chars > 1:
      print('NO')
  else:
      print('YES')
  
subject: Create got1.py