#!/bin/python3

import sys

def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    lst = [0, 0, 0, 0]
    for ch in password:
        if lst[0] == 0 and ch in numbers:
            lst[0] = 1
        if lst[1] == 0 and ch in lower_case:
            lst[1] = 1
        if lst[2] == 0 and ch in upper_case:
            lst[2] = 1
        if lst[3] == 0 and ch in special_characters:
            lst[3] = 1
    need = 4 - sum(lst)
    return max(need, 6-n)

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