#!/bin/python3

import sys
numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"
def minimumNumber(n, password):
    gerek = 4
    sayi = 0;buyuk = 0;kucuk = 0;ozel = 0
    for i in password:
        if sayi == 0 and i in numbers: #sayi iceriyo mu
            gerek -= 1
            sayi = 1
            continue
        elif buyuk == 0 and i in upper_case:
            gerek -= 1
            buyuk = 1
            continue
        elif kucuk == 0 and i in lower_case:
            gerek -= 1
            kucuk = 1
            continue
        elif ozel == 0 and i in special_characters:
            gerek -= 1
            ozel = 1
            continue
    if gerek > 6 - len(password):
        return gerek
    else:
        return 6 - len(password)
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)