#!/bin/python3

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    noSpecial = 1
    noDigit = 1
    noLower = 1
    noUpper = 1
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    
    for ele in numbers:
        if ele in password:
            noDigit = 0
    for ele in lower_case:
        if ele in password:
            noLower = 0
    for ele in upper_case:
        if ele in password:
            noUpper = 0
    for ele in special_characters:
        if ele in password:
            noSpecial = 0
    finalNumber = max(noDigit+noLower+noUpper+noSpecial,6-n)
    return finalNumber
    
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)