#!/bin/python3

import sys

def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    numbers = "0123456789"
    lower_c = "abcdefghijklmnopqrstuvwxyz"
    upper_c = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_ch = "!@#$%^&*()-+"
    has_numbers =False
    has_lower_c =False
    has_upper_c=False
    has_special_ch=False
    has_length=False
    
    if n>5:
        has_length=True
    for i in range(n):
        if has_numbers==False:
             if password[i] in numbers:
                has_numbers=True
                
        if has_lower_c==False:    
            if password[i] in lower_c:
                has_lower_c=True 
                
        if has_upper_c==False:    
            if password[i] in upper_c:
                has_upper_c=True
                
        if has_special_ch==False:    
            if password[i] in special_ch:
                has_special_ch=True 
                
    required_cond=4-(has_numbers+has_lower_c + has_upper_c + has_special_ch)
    #print("arrived")
    if has_length==True:
        return required_cond
    
    a=6-n 
    return max(a , required_cond)
    
if __name__ == "__main__":
        n = int(input().strip())
        password = input().strip()
        answer = minimumNumber(n, password)
        print(answer)