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 spl = "!@#$%^&*()-+";
        int retVal = 0;
        boolean digitFound = false;
        boolean upFound = false;
        boolean loFound = false;
        boolean splFound = false;
        
        
        if(n < 6) {            
            return 6 - n;            
        } 
        for(int i = 0; i < n; i++) {
            if(Character.isDigit(password.charAt(i))) {
                digitFound = true;
            } 
            if(Character.isUpperCase(password.charAt(i))) {
                upFound = true;
            }
            if(Character.isLowerCase(password.charAt(i))) {
                loFound = true;
            }
            if(spl.indexOf(password.charAt(i)) != -1){
                splFound = true;
            }
        }
        if(!digitFound) {
            retVal++;
        }
        if(!upFound) {
            retVal++;
        }
        if(!loFound) {
            retVal++;
        }
        if(!splFound) {
            retVal++;
        }
        return retVal;
    }

    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();
    }
}