#!/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 = "!@#$%^&*()-+"
    '''
Its length is at least 6.
It contains at least one digit.
It contains at least one lowercase English character.
It contains at least one uppercase English character.
It contains at least one special character. The special characters are
    '''
    need = 0
    chk = [False,False,False,False]
    for i in password:
        if i.isdigit(): chk[0]=True
        if i in lower_case: chk[1]=True
        if i in upper_case: chk[2]=True
        if i in special_characters: chk[3]=True
    need = chk.count(False)
   # print(chk)
    if need+n<6: need+= 6-need-n
    return need

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