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 len=6,dig=1,lower=1,upper=1,special=1,num=0;
        for(int i=0;i<n;i++)
        {
            if(len<=0 && dig<=0 && lower<=0 && upper<=0 && special<=0)
                return 0;
            if(password.charAt(i)>=48 && password.charAt(i)<=57)
                dig--;
            else if(password.charAt(i)>=97 && password.charAt(i)<=122)
                lower--;
            else if(password.charAt(i)>=65 && password.charAt(i)<=90)
                upper--;
            else if((password.charAt(i)>=35 && password.charAt(i)<=38)||(password.charAt(i)>=40 && password.charAt(i)           <=43)||password.charAt(i)==33||password.charAt(i)==45||password.charAt(i)==64||password.charAt(i)==94)
                special--;
            len--;
        }
        if(dig>0)
        {
            num++;
           // len--;
        }
        if(lower>0)
        {
        num++;
        //len--;
        }
            if(upper>0)
            {
                num++;
              //  len--;
            }
        if(special>0)
        {
            num++;
           // len--;
        }
        return num>len?num:len;
        // Return the minimum number of characters to make the password strong
    }

    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();
    }}