#!/bin/python3

import sys

def minimumNumber(n, password):
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    bool1=bool2=bool3=bool4=False
    count2=0
    if(len(password)>=6):
        count=0
    else:
        count=6-len(password)
    for x in password:
        if x in numbers:
            bool1=True
        if x in lower_case:
            bool2=True
        if x in upper_case:
            bool3=True
        if x in special_characters:
            bool4=True
    if bool1==False:
        count2+=1
    if bool2==False:
        count2+=1
    if bool3==False:
        count2+=1
    if bool4==False:
        count2+=1
    #print(bool1,bool2,bool3,bool4,count)
    return(max(count,count2))
if __name__ == "__main__":
    n = int(input().strip())
    password = input().strip()
    answer = minimumNumber(n, password)
    print(answer)