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 needsUpper = true;
        boolean needsLower = true;
        boolean needsDigit = true;
        boolean needsSpecial = true;
        
        String special_characters = "!@#$%^&*()-+";
            
        for(int i = 0; i < n; i++) {
            if(needsUpper && password.charAt(i) >= 'A' && password.charAt(i) <= 'Z') {needsUpper = false;}
            if(needsLower && password.charAt(i) >= 'a' && password.charAt(i) <= 'z') {needsLower = false;}
            if(needsDigit && password.charAt(i) >= '0' && password.charAt(i) <= '9') {needsDigit = false;}
            if(needsSpecial && special_characters.contains("" + password.charAt(i))) {needsSpecial = false;}
        }
        
        int errors = (needsUpper? 1 : 0) + (needsLower? 1 : 0) + (needsDigit? 1 : 0) + (needsSpecial? 1 : 0);
        
        return Math.max(errors, 6-n);
    }

    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();
    }
}