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

public class Solution {
    
    static String numbers = "0123456789";
    static String lower_case = "abcdefghijklmnopqrstuvwxyz";
    static String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    static String special_characters = "!@#$%^&*()-+";

    static int minimumNumber(int n, String password) {
        int num = 0;
        int low = 0;
        int upp = 0;
        int spec =0;
        for(int i=0; i<n; i++){
            for(int j=0; j<numbers.length(); j++){
                if(num == 0 && password.charAt(i) == numbers.charAt(j)) num++;  
            }    
            for(int j=0; j<lower_case.length(); j++){
                if(low == 0 && password.charAt(i) == lower_case.charAt(j)) low++;
            }    
            for(int j=0; j<upper_case.length(); j++){
                if(upp == 0 && password.charAt(i) == upper_case.charAt(j)) upp++;
            }    
            for(int j=0; j<special_characters.length(); j++){
                if(spec == 0 && password.charAt(i) == special_characters.charAt(j)) spec++;
            }    
        }
        int result=0;
        
        if(n>=6){
            result = 4-(num+low+upp+spec);
        }else{
            if(4-(num+low+upp+spec)>=(6-n)){
                result = 4-(num+low+upp+spec);
            }else{
                result = 6-n;
            }
        }
        
        return result;
    }

    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();
    }
}