#!/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 = "!@#$%^&*()-+"
    c1=0
    c2=0
    c3=0
    c4=0
    for i in password:
        if i in numbers:
            c1+=1
        if i in lower_case:
            c2+=1
        if i in upper_case:
            c3+=1
        if i in special_characters:
            c4+=1
    count=0
    if c1==0:
        count+=1
    if c2==0:
        count+=1
    if c3==0:
        count+=1
    if c4==0:
        count+=1
    if n<6:
        if 6-n>count:
            count+=6-n-count
    return count

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