#!/bin/python
requirements = dict(
numbers = set("0123456789"),
lower_case = set("abcdefghijklmnopqrstuvwxyz"),
upper_case = set("ABCDEFGHIJKLMNOPQRSTUVWXYZ"),
special_characters = set("!@#$%^&*()-+"))

import sys

def minimumNumber(n, password):
    not_seen = set(requirements)
    for i in xrange(n):
        for k, s in requirements.items():
            if password[i] in s and k in not_seen:
                not_seen.remove(k)
                break
    
    chars_needed = len(not_seen)
    
    chars_needed_for_min_length = 6 - (n + chars_needed)
    if chars_needed_for_min_length > 0:
        chars_needed += chars_needed_for_min_length
    
    return chars_needed
    
    
    
    # Return the minimum number of characters to make the password strong

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