Envío 4773

Código

from collections import Counter

def decrement_and_delete(cnt, c):
    if cnt[c] == 1:
        del cnt[c]
    else:
        cnt[c] -= 1

def max_k(s, k):
    l = r = 0
    w = Counter()
    res = 0
    while r < len(s):
        while l <= len(s) and len(w) > k:
            decrement_and_delete(w, s[l])
            l += 1
        res = max(res, r - l)
        w[s[r]] += 1
        r += 1
    if len(w) <= k:
        res = max(res, r - l)
    return res
  
if __name__ == "__main__":
    s = input()
    k = int(input())
    print(max_k(s, k))