def isValid(s):
    # Write your code here
    holder = {}
    for char in s:
        if char in holder:
            holder[char] += 1
        else:
            holder[char] = 1
    val = list(holder.values())
    val.sort()
    test1 = set(val[1:])
    test2 = set(val[:-1])
    test2.add(val[-1]-1)
    result = "YES" if len(test1) == 1 or len(test2) == 1 else "NO"
    return result