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
        char []c=password.toCharArray();
        int p=4,flagn=0,flags=0,flagb=0,flagx=0;
        
            for(int i=0;i<n;i++)
            {
                if(c[i]>='0'&&c[i]<='9')
                {
                    if(flagn==0)
                    {
                        p--;
                        flagn=1;
                    }
                }
                else if(c[i]>='a'&&c[i]<='z')
                {
                    if(flags==0)
                    {
                        p--;
                        flags=1;
                    }
                }
                else if(c[i]>='A'&&c[i]<='Z')
                {
                    if(flagb==0)
                    {
                        p--;
                        flagb=1;
                    }
                }
                else
                {
                     if(flagx==0)
                    {
                        p--;
                        flagx=1;
                    }
                }
                
            }
            
        if(n<6)
        {
            if(n+p>=6)
                return p;
            else
                return (6-n);
        }
        
        return p;
            
        
    }

    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();
    }
}