#!/bin/python3

import sys

numbers = set("0123456789")
lower_case = set("abcdefghijklmnopqrstuvwxyz")
upper_case = set("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
special_characters = set("!@#$%^&*()-+")

def minimumNumber(n, password):
    password_set = set(password)
    has_digit = any(x in numbers for x in password_set)
    has_lower = any(x in lower_case for x in password_set)
    has_upper = any(x in upper_case for x in password_set)
    has_special = any(x in special_characters for x in password_set)
    res = max(6-n, 4-int(has_digit)-int(has_lower)-int(has_upper)-int(has_special))
    return res

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