#!/bin/python

import sys

def minimumNumber(n, password):
    counter = 0
    charset = set()
    numbers = set(list("0123456789"))
    lower_case = set(list("abcdefghijklmnopqrstuvwxyz"))
    upper_case = set(list("ABCDEFGHIJKLMNOPQRSTUVWXYZ"))
    special_characters = set(list("!@#$%^&*()-+"))
    numbers_b = False
    lower_case_b = False
    upper_case_b = False
    special_characters_b = False
    
    
    for charr in password:
        if charr in numbers:
            numbers_b = True
        if charr in lower_case:
            lower_case_b = True
        if charr in upper_case:
            upper_case_b = True
        if charr in special_characters:
            special_characters_b = True
    
    for boolean in [numbers_b,lower_case_b,upper_case_b,special_characters_b]:
        if boolean == False:
            counter += 1
    
    return max(6 - n,counter)
            
        
    

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