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 s) {
        int lo=0, up=0, sc=0, dig=0, req=0;
        int l=s.length();
        char[] ch=s.toCharArray();
        
        for(int i=0; i<l; i++)  {
            
            if(ch[i]>='0' && ch[i]<='9')
                dig++;
            else if(ch[i]>='A' && ch[i]<='Z')
                up++;
            else if(ch[i]>='a' && ch[i]<='z')
                lo++;
            else
                sc++;
        }
        if(dig==0)
            req++;
        if(up==0)
            req++;
        if(lo==0)
            req++;
        if(sc==0)
            req++;
        if(l+req<6)
            req+=6-l-req;
        
        return req;
        
    }

    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();
    }
}