#!/bin/python

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    newpassword = password
    auxdict = {}
    letters = ["n", "l", "u", "s"]
    toadd = []
    for character in password:
        if character in numbers:
            auxdict["n"] = 1
        elif character in lower_case:
            auxdict["l"] = 1
        elif character in upper_case:
            auxdict["u"] = 1
        elif character in special_characters:
            auxdict["s"] = 1
    for letter in letters:
        if letter not in auxdict:
            toadd.append(letter)
    if not toadd:
        if n >=6:
            return 0
        else:
            return 6 - n
    else:
        if n+len(toadd) >= 6:
            return len(toadd)
        else:
            return 6-n
        
if __name__ == "__main__":
    n = int(raw_input().strip())
    password = raw_input().strip()
    answer = minimumNumber(n, password)
    print answer