#!/bin/python

import sys

str_numbers = "0123456789"
str_lcase = "abcdefghijklmnopqrstuvwxyz"
str_ucase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
str_special = "!@#$%^&*()-+"
min_len = 6

def minimumNumber(n, password):
    num_dig = 0
    num_low = 0
    num_hig = 0
    num_spc = 0
    for c in password:
        num_dig += str_numbers.count(c)
        num_low += str_lcase.count(c)
        num_hig += str_ucase.count(c)
        num_spc += str_special.count(c)
    min_add = max(0, min_len - n)
    min_req = 0
    if num_dig == 0: min_req += 1
    if num_low == 0: min_req += 1
    if num_hig == 0: min_req += 1
    if num_spc == 0: min_req += 1
    return max(min_req, min_add)
    
    
if __name__ == "__main__":
    n = int(raw_input().strip())
    password = raw_input().strip()
    answer = minimumNumber(n, password)
    print answer