Envío 2194

Código

import math

def min_substr(s, k):
    i = 0
    n = len(s)
    curr_min = float("inf")
    letters = dict()

    for j in range(n):
        l = s[j]
        cl = letters.get(l, 0)
        letters[l] = cl + 1

        while len(letters) >= k:
            curr_min = min(curr_min, j - i + 1)
            l = s[i]
            cl = letters[l]
            letters[l] = cl - 1

            if letters[l] == 0:
                del letters[l]
            i = i + 1
    
    return -1 if math.isinf(curr_min) else curr_min

s = input()
k = int(input())
print(min_substr(s, k))