#!/bin/python

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    l = list (numbers)
    a = 0
    ok = False
    for i in l:
        if i in password:
            ok = True
    if not ok: a += 1
    ok = False
    l = list (lower_case)
    for i in l:
        if i in password:
            ok = True
    if not ok: a += 1
    ok = False
    l = list (upper_case)
    for i in l:
        if i in password:
            ok = True
    if not ok: a += 1
    ok = False
    l = list (special_characters)
    for i in l:
        if i in password:
            ok = True
    if not ok: a += 1
    return max (a, 6 - len (password))

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