#!/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 = "!@#$%^&*()-+"
    h, f = 0, 0
    for i in numbers:
        if i in password:
            f = 1
            break
    if f==0:
        h+=1
    f = 0
    for i in lower_case:
        if i in password:
            f=1
            break
    if f==0:
        h+=1
    f = 0
    for i in upper_case:
        if i in password:
            f=1
            break
    if f==0:
        h+=1
    f = 0
    for i in special_characters:
        if i in password:
            f=1
            break
    if f==0:
        h+=1
    return max(h, 6-n)        
            

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