#python
from collections import Counter
def happyLadybugs(b):
    c=Counter(b).items()
    for x in c:
        if x[0]!='_' and x[1]==1:
            return "NO"
    if '_' not in b:
        for i in range(len(b)-1):
            if b[i]==b[i+1] or b[i]==b[i-1]:
                continue
            else:
                return "NO"
    return "YES"