#!/bin/python3

import sys

numbers = {c for c in "0123456789"}
lower_case = {c for c in "abcdefghijklmnopqrstuvwxyz"}
upper_case = {c for c in "ABCDEFGHIJKLMNOPQRSTUVWXYZ"}
special_characters = {c for c in "!@#$%^&*()-+"}

def contains_char(s1, s2):
    return len(s1 & s2) > 0

def minimumNumber(n, password):
    to_add = 0
    pw_set = {p for p in password}
    for req_set in [numbers, lower_case, upper_case, special_characters]:
        if not contains_char(pw_set, req_set):
            to_add += 1
    if len(password) >= 6:
        return to_add
    else:
        return max(6 - len(password), to_add)
    

if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)