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 result =0;
        int length_short =0;
        if(n<6)
        {
            length_short =6-n;
        }
        int[] arr =new int[4];
        
        for(int i=0;i<n;i++)
        {
            int num=(int)password.charAt(i);
            if(num>47&&num<58)
            {
                arr[0]=1;
            }
            else if(num>96 && num<123)
            {
                arr[1]=1;
            }
            else if(num>64 && num<91)
            {
                arr[2]=1;
            }
            else
            {
                if(password.charAt(i)=='!'||password.charAt(i)=='@'||password.charAt(i)=='%'||password.charAt(i)=='#'||password.charAt(i)=='^'||password.charAt(i)=='&'||password.charAt(i)=='('||password.charAt(i)==')'||password.charAt(i)=='-'||password.charAt(i)=='+')
                {
                    arr[3]=1;
                }
            }
            
            
            
            
            
        }
        int total =arr[0]+arr[1]+arr[2]+arr[3];
            total =4-total;
        if(length_short>total)
            {
                return length_short;
            }
            else
            {
                return total;
            }
    }

    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();
    }
}