#!/bin/python3

import sys

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

def minimumNumber(n, password):
    ncase = False
    lcase = False
    ucase = False
    scase = False
    for x in range(n):
        l = password[x]
        if l in numbers:
            ncase = True
        if l in lower_case:
            lcase = True
        if l in upper_case:
            ucase = True
        if l in special_characters:
            scase = True
    y = sum([1 for i in [ncase, lcase, ucase, scase] if not i])
    if n + y >= 6:
        return y
    else:
        return 6 -n
    # Return the minimum number of characters to make the password strong
    

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