#!/bin/python

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 = "!@#$%^&*()-+"
    ans=0
    for i in numbers:
        if password.count(i)>0:
            ans=ans+1
            break
    for i in lower_case:
        if password.count(i)>0:
            ans=ans+1
            break
    for i in upper_case:
        if password.count(i)>0:
            ans=ans+1
            break
    for i in special_characters:
        if password.count(i)>0:
            ans=ans+1
            break
    if len(password)<6:
        return max(6-len(password),4-ans)
    return 4-ans
            

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