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) {
        // Return the minimum number of characters to make the password strong
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        
        int len = n;
        int digit = 0;
        int lower = 0;
        int upper = 0;
        int special = 0;
        
        for(int i = 0; i < n; i++) {
            char c = password.charAt(i);
            if(numbers.indexOf(c) != -1) {
                digit++; 
                continue;
            }
            if(lower_case.indexOf(c) != -1) {
                lower++; 
                continue;
            }
            if(upper_case.indexOf(c) != -1) {
                upper++; 
                continue;
            }
            if(special_characters.indexOf(c) != -1) {
                special++; 
                continue;
            }
        }
        
        int ans = 0;
        
        if(digit == 0) ans++;
        if(lower == 0) ans++;
        if(upper == 0) ans++;
        if(special == 0) ans++;
        //System.out.println(numbers.indexOf('3'));
//        System.out.println("digit: " + digit + " lower: " + lower + " upper: " + upper + " special: " + special );
        if(ans + n < 6) ans = 6 - n;
        
        return ans;
    }

    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();
    }
}