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
        int count=4;
        boolean lower=false,upper=false,digit=false,special=false;
        for(int i=0;i<password.length();i++){
            int ch=(int)password.charAt(i);
            if(ch>=97&&ch<=122){
                if(!lower){
                count--;
                lower=true;
                }
            }
            else if(ch>=65&&ch<=90){
               if(!upper){
                count--;
                upper=true;
                }
            }
            else if(ch>=48&&ch<=57){
                if(!digit){
                count--;
                digit=true;
                }
            }
            else if(!special){
                int a[]={'!','@','#','$','%','^','&','*','(',')','-','+'};
		          for(int j=0;i<a.length;j++){
				    if(a[j]==ch){
                        special=true;
                        count--;
                        break;
                    }
            }
             
        }
    }
         if(count+password.length()>=6){
                  return count;
              }
                else{
                   
                    return 6-password.length();
                }
    }

    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();
    }
}