#!/bin/python3

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    if n==0:
        return 6
    
    uppers, lowers, digits, characs = 0, 0, 0, 0
    for l in password:
        if l.isupper():
            uppers += 1
        elif l.islower():
            lowers += 1
        elif l.isdigit():
            digits += 1
        elif not l.isalnum():
            characs += 1
   
    #caculate what is needed
    content_req=max(0,1-uppers)+max(0,1-lowers)+max(0,1-digits)+max(0,1-characs)
    length_req=max(0,6-n)
    
    #print(content_req, length_req)
    
    return max(content_req,length_req)
   
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)