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 p) {
       boolean low=false;
        boolean up=false;
        boolean dig=false;
        boolean spc=false;
        String sp= "!@#$%^&*()-+";
        for(int i=0;i<p.length();i++){
            char c=p.charAt(i);
            for(int j=0;j<sp.length();j++){
                if(sp.charAt(j)==c)
                    spc=true;
            }
            if(c>='A'&&c<='Z'){
                up=true;
            }
            if(c>='a'&&c<='z'){
                low=true;
            }
            if(c>='0'&&c<='9'){
                dig=true;
            }
        }
        int c=0;
        if(!up)
            c++;
        if(!low)
            c++;
        if(!dig)
            c++;
        if(!spc)
            c++;
        if(n<6)
            c=Math.max(6-n,c);
        return c;
    }

    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();
    }
}