#!/bin/python

import sys

def minimumNumber(n, password):
    
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    contain_lower = False
    contain_upper = False
    contain_special = False
    contain_number = False
    
    length = len(password)
    
    for char in password:
        if (char in lower_case):
            contain_lower = True
        elif (char in upper_case):
            contain_upper = True
        elif (char in special_characters):
            contain_special = True
        elif (char in numbers):
            contain_number = True
    
    addition = 4
    if (contain_lower):
        addition-=1
    if (contain_upper):
        addition -=1
    if (contain_special):
        addition -=1
    if (contain_number):
        addition -=1
    
   
    if (n<6):
        if (addition+length<=6):
            return (6-length)
        else :
            return (6-length+(addition-6+length))
    else :
        return addition
     
    # Return the minimum number of characters to make the password strong

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