#! /usr/bin/env python

n = int(raw_input().strip())
password = raw_input().strip()

numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special = "!@#$%^&*()-+"

has_numbers = any([x in numbers for x in password])
has_lower_case = any([x in lower_case for x in password])
has_upper_case = any([x in upper_case for x in password])
has_special = any([x in special for x in password])

len_missing = max(0, 6 - len(password))
char_missing = 0
if not has_numbers:
    char_missing += 1
if not has_lower_case:
    char_missing += 1
if not has_upper_case:
    char_missing += 1
if not has_special:
    char_missing += 1

print max(len_missing, char_missing)