"""
출처:프로그래머스,
https://school.programmers.co.kr/learn/courses/30/lessons/132265
"""

# 풀이과정
def solution(topping):
    from collections import Counter
    k = Counter(topping)
    check = set()
    result = 0

    for a in topping:
        k[a] -= 1
        check.add(a)
        if k[a] == 0:
            del k[a]

        if len(k) == len(check):
            result += 1

    return result