#!/bin/python3

import sys
numbers = "0123456789"
lower_case = "abcdefghijklmnopqrstuvwxyz"
upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
special_characters = "!@#$%^&*()-+"
def minimumNumber(n, password):
    mini=0
    num=False
    low=False
    up=False
    spec=False
    if n<6:
        mini=6-n
    for x in password:
        if x in numbers:
            num=True
        elif x in lower_case:
            low=True
        elif x in upper_case:
            up=True
        elif x in special_characters:
            spec=True
    defic=0
    if num==False:
        defic+=1
    if low==False:
        defic+=1
    if up==False:
        defic+=1
    if spec==False:
        defic+=1
    if mini<defic:
        mini=defic
    return mini
    
    

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