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

public class Solution {

    static int minimumNumber(int n, String password) {
        // Return the minimum number of characters to make the password strong
        
        char pass[] = password.toCharArray();
        boolean digit = true;
        boolean lowercase = true;
        boolean uppercase = true;
        boolean specialchar = true;
        int required = 4;
        for (int i =0;i<n;i++){

                        if (digit && Character.isDigit(pass[i])){
                required--;
                digit = false;
            }
            
            
            
            if (lowercase && Character.isLowerCase(pass[i])){
                required--;
                lowercase = false;
            }
            
            
            
            if (uppercase && Character.isUpperCase(pass[i])){
                required--;
                uppercase = false;
            }
            
            
                       if (specialchar && ( pass[i] == '!' || pass[i] == '@' || pass[i] == '#' || pass[i] == '$' || pass[i] == '%' || pass[i] == '^' || pass[i] == '&' || pass[i] == '*' || pass[i] == '(' || pass[i] == ')' || pass[i] == '-' || pass[i] == '+' ) ){
                required--;
                specialchar = false;
            }
            
        }
        
    if (n + required >=6) {
        return required;
    }
        
    if (6-n > required){
        return 6-n;
    }
      else{
          return required;  
        }
    }

    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();
    }
}