import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static int minimumNumber(int n, String password) {
        String numbers = "0123456789";
    String lower_case = "abcdefghijklmnopqrstuvwxyz";
    String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    String special_characters = "!@#$%^&*()-+";
        int ar[]={0,0,0,0};
        for(int i=0;i<numbers.length();i++)
            if(password.indexOf(numbers.charAt(i))!=-1)
            {
                ar[0]=1;
                break;
            }
        for(int i=0;i<lower_case.length();i++)
        {if(password.indexOf(lower_case.charAt(i))!=-1)
            {
                ar[1]=1;
                break;
            }}
        for(int i=0;i<upper_case.length();i++)
            if(password.indexOf(upper_case.charAt(i))!=-1)
            {
                ar[2]=1;
                break;
            }
        for(int i=0;i<special_characters.length();i++)
            if(password.indexOf(special_characters.charAt(i))!=-1)
            {
                ar[3]=1;
                break;
            }int c=0;
        for(int i=0;i<4;i++)
            if(ar[i]==0)
             c++;
        if(n<6)
        {
            if(c>(6-n))
             return c;
            else
                return (6-n);
        }
        else
            return c;
        
        
            
        // Return the minimum number of characters to make the password strong
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String password = in.next();
        int answer = minimumNumber(n, password);
        System.out.println(answer);
        in.close();
    }
}