#!/bin/python

import sys

def minimumNumber(n, s):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"

    num=False
    low = False
    upp = False
    sp = False

    for i in range(0,len(numbers)):
        if(numbers[i] in s):
            num=True

    for i in range(0,len(lower_case)):
        if(lower_case[i] in s):
            low=True

    for i in range(0,len(upper_case)):
        if(upper_case[i] in s):
            upp=True

    for i in range(0,len(special_characters)):
        if(special_characters[i] in s):
            sp=True

    count=0
    if num==False:
        count+=1
    if low==False:
        count+=1
    if upp==False:
        count+=1
    if sp==False:
        count+=1

    return (max(count,6-len(s)))

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