from collections import Counter

def gameOfThrones(s):
    counter = Counter(s)
    middle = 0

    if not len(s) // 2:  # even
        for k,v in counter.items(): 
            if v // 2: 
                return "NO"
    else:
        for k,v in counter.items():
            if v % 2 == 1:
                middle += 1
    if middle > 1:
        return "NO"
    return "YES"