#!/bin/python3

import sys

def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    num_present = False
    lower_present = False
    upper_present = False
    symbol_present = False
    for let in password:
        let_ord = ord(let)
        if let in lower_case:
            lower_present = True
        elif let in upper_case:
            upper_present = True
        elif let in numbers:
            num_present = True
        elif let in special_characters:
            symbol_present = True
    #print([num_present,lower_present,upper_present,symbol_present])
    return max([6-n, sum((int(not ans) for ans in [num_present,lower_present,upper_present,symbol_present]))])
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)