#!/bin/python3

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    
    numbers = set("0123456789")
    lower_case = set("abcdefghijklmnopqrstuvwxyz")
    upper_case = set("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
    special_characters = set("!@#$%^&*()-+")
    
    pas = set(password)
    count = 0
    
    if len( numbers & pas ) == 0:
        count += 1
    if len( lower_case & pas ) == 0:
        count += 1
    if len( upper_case & pas ) == 0:
        count += 1
    if len( special_characters & pas ) == 0:
        count += 1    
        
    return max(6-n, count)
    

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