new_contents: from collections import Counter
  string = raw_input()
  
  s = 0
  c = Counter(string)
  for i in c.values():
  	if i % 2 == 1:
  		s += 1
  if s <= 1:
  	found = True
  else:
  	found = False
  # Write the code to find the required palindrome and then assign the variable 'found' a value of True or False
  
  if not found:
      print("NO")
  else:
      print("YES")
  
  
subject: add game_of_thrones