#!/bin/python3

import sys
import re

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

def minimumNumber(n, password):
    nFlag = 1 if re.findall('\d+', password) == [] else 0
    lcFlag = 1 if re.findall(r"[a-z]",password) == [] else 0
    ucFlag = 1 if re.findall(r"[A-Z]",password) == [] else 0
    scFlag = 1 if re.findall(r"[^A-Za-z0-9]+", password) == [] else 0
    return max(6 - len(password), nFlag+lcFlag+ucFlag+scFlag)
    
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)