#!/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 = "!@#$%^&*()-+"
    
    is_number = False;
    is_lower = False;
    is_upper = False;
    is_special = False;
    rs = 0;
    for i in range(0,len(password)):
        if password[i] in numbers:
            is_number = True
        elif password[i] in lower_case:
            is_lower = True
        elif password[i] in upper_case:
            is_upper = True
        elif password[i] in special_characters:
            is_special = True
        if is_number and is_lower and is_upper and is_special:
            break;
    if not is_number:
        rs += 1
    if not is_lower:
        rs += 1
    if not is_upper:
        rs += 1
    if not is_special:
        rs += 1
        
    if n < 6:
        if 6-n < rs:
            return str(rs)
        return str(6-n)
        
    return str(rs)

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