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) {
       int min=0;
        int flag=0;
        int len=password.length();
        if(len<6)
            flag=1;
       int up=1,low=1,dig=1,spe=1;
       for(int i=0;i<n;i++)
       {
           if(password.charAt(i)>='A' && password.charAt(i)<='Z')
               up--;
           else if(password.charAt(i)>='a' && password.charAt(i)<='z')
               low--;
           else if(password.charAt(i)>='0' && password.charAt(i)<='9')
                dig--;
            else if(password.charAt(i)>='!' && password.charAt(i)<='@')
                spe--;
       }
        if(up>0)
            min++;
        if(low>0)
            min++;
        if(dig>0)
            min++;
        if(spe>0)
            min++;
        
        if(flag==1)
        {
            int k=0;
            n=n+min;
            if(n<6)
            {
                k=6-n;
                min=min+k;
            }
            
        }
        return min;
    }

    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();
    }
}