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
        boolean digit = false, lower = false, upper = false, special = false;
        for(int i = 0; i < n; i++){
            if(password.charAt(i) <= 'z' && password.charAt(i) >= 'a')
                lower = true;
            else if(password.charAt(i) <= 'Z' && password.charAt(i) >= 'A')
                upper = true;
            else if(password.charAt(i) <= '9' && password.charAt(i) >= '0')
                digit = true;
            else{
                switch(password.charAt(i)){
                    case '!':
                    case '@':
                    case '#':
                    case '$':
                    case '%':
                    case '^':
                    case '&':
                    case '*':
                    case '(':
                    case ')':
                    case '-':
                    case '+':
                        special = true;
                        break;
                }
            }
        }
        
        int count = 0;
        if(lower)
            count++;
        if(upper)
            count++;
        if(digit)
            count++;
        if(special)
            count++;
        
        int res = 4 - count;
        if(res + n < 6)
            res += 6 - res - n;
        
        return res;
    }

    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();
    }
}