#!/bin/python3

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 = "!@#$%^&*()-+"
    flag=0
    for i in password:
        if i in numbers:
            numbers=''
            flag+=1
        elif i in lower_case:
            lower_case=''
            flag+=1
        elif i in upper_case:
            upper_case=''
            flag+=1
        elif i in special_characters:
            special_characters=''
            flag+=1
    return 4-flag if 4-flag>6-len(password) else 6-len(password)
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)