#!/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 = "!@#$%^&*()-+"
    l=[0 for x in range(4)]
    c=0
    
    for j in password:
            if j in numbers:
                l[0]+=1
            if j in lower_case:
                l[1]+=1
            if j in upper_case:
                l[2]+=1
            if j in special_characters:
                l[3]+=1
    for x in l:
            if(x==0):
                c+=1
    if(n+c<6):
       c=c+(6-n-c)
    return c
if __name__ == "__main__":
    n = int(raw_input().strip())
    password = raw_input().strip()
    answer = minimumNumber(n, password)
    print answer