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) {
        boolean lcase=false;
        boolean ucase=false;
        boolean digit=false;
        boolean spChar=false;
        int min=4;
        for(int i=0;i<n;i++){
            int c = (int)password.charAt(i);
            if(!lcase && c>=65 && c<=90){
                lcase=true;
                min--;
                continue;
            }
            if(!ucase && c>=97 && c<=122){
                ucase=true;
                min--;
                continue;
            }
            if(!spChar){
                char ch=(char)c;
                if(ch=='!' || ch=='#' || ch=='@' || ch=='$' || ch=='%' || ch== '^' || ch=='&' || ch=='*' || ch=='(' || ch==')' || ch=='+' || ch=='-'){
                    spChar=true;
                    min--;
                    continue;
                }
            }
            if(!digit && c>=48 && c<=57){
                digit=true;
                min--;
                continue;
            }
            
        }
        if(n<6){
            if(min>(6-n)){
                return min;
            }else{
                return 6-n;
            }
        }else{
            return min;
        }
        // Return the minimum number of characters to make the password strong
    }

    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();
    }
}