#!/bin/python

import sys
numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    #1 = int(len(set(numbers).intersection(password)))==0 + int(lower_case not in password) + int(special_characters not in password)
    x1 = int(len(set(numbers).intersection(set(password))) == 0) + int(len(set(special_characters).intersection(set(password))) == 0) + int(len(set(lower_case).intersection(set(password))) == 0) + int(len(set(upper_case).intersection(set(password))) == 0)
    x2 = max(0, 6 - n)
    return max(x1, x2) 


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