#!/bin/python3

import sys
import string
def minimumNumber(n, password):
    special_characters = "!@#$%^&*()-+"
    c=0
    if len(set(string.ascii_lowercase)-set(password))==26:
        c+=1
    if len(set(string.ascii_uppercase)-set(password))==26:
        c+=1
    if len(set(string.digits)-set(password))==10:
        c+=1
    if len(set(string.punctuation)-set(password))==len(string.punctuation):
        c+=1
    if c==0 and n>=6:
        return 0
    elif n>=6 and c!=0:
        return c
    elif n<6:
        if 6-n<c:
            return c
        else:
            return 6-n
            
        
        

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