题解 | 穷哈哈~

n = int(input())
s = input()

max_len = 0
cur_len = 0

for i in range(n):
    if s[i] == 'a' or s[i] == 'h':  # 当前字符是 a 或 h
        if cur_len == 0:
            cur_len = 1  # 开始新序列
        elif (s[i] == 'a' and s[i-1] == 'h') or (s[i] == 'h' and s[i-1] == 'a'):
            cur_len += 1  # 与前一个字符交替，继续延伸
        else:
            cur_len = 1  # 连续相同字符(aa/hh)，重新开始
    else:
        cur_len = 0  # 遇到非a非h字符，序列断开

    max_len = max(max_len, cur_len)

print(max_len)