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) {
        int countNum, countLowerCase, countUpperCase, countSpecial;
        countNum = 0;
        countLowerCase = 0;
        countUpperCase = 0 ;
        countSpecial = 0;
        
        char[] numbers = "0123456789".toCharArray();
        char[] lowerCase = "abcdefghijklmnopqrstuvwxyz".toCharArray();
        char[] upperCase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
        char[] speciaCharacters = "!@#$%^&*()-+".toCharArray();
            
        for (int i=0; i<n; i++){ 
            for (int j=0; j<numbers.length; j++){
                if (password.charAt(i) == numbers[j]){
                    countNum++;
                    break;
                }
            }
            for (int j=0; j<lowerCase.length; j++){
                if (password.charAt(i) == lowerCase[j]){
                    countLowerCase++;
                    break;
                }
            }
            for (int j=0; j<upperCase.length; j++){
                if (password.charAt(i) == upperCase[j]){
                    countUpperCase++;
                    break;
                }
            }            
            for (int j=0; j<speciaCharacters.length; j++){
                if (password.charAt(i) == speciaCharacters[j]){
                    countSpecial++;
                    break;
                }
            }
        }
        
  
        int result=0;
        
        if (countNum < 1)
            result++;
        if (countLowerCase < 1)
            result++;
        if (countUpperCase < 1)
            result++;
        if (countSpecial < 1)
            result++;
        int errors = result;

        
        if (n < 6)
            result = 6 - n;
        
        if (result < errors)
            result = result + (errors - result);
        
        
        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();
    }
}