HDNL Toy

import java.util.Scanner;
import java.util.Stack;

public class HDNL {

    public static void main(String[] args) {


        Scanner sc = new Scanner(System.in);

        int n = Integer.parseInt(sc.nextLine());
        Stack<Integer> ranks = new Stack<>();
        Stack<String> closingTags = new Stack<>();
        int indent = 0;
        StringBuilder output = new StringBuilder();
        for (int i = 0; i < n; i++) {
            String inputLine = sc.nextLine();
            int rank = Integer.parseInt(inputLine.substring(1));

            while(!ranks.isEmpty() && ranks.peek()>=rank) {
                ranks.pop();
                String tag = closingTags.pop();
                indent--;
                printTag(output, indent, tag, "</%s>%n");
            }

                printTag(output, indent,inputLine, "<%s>%n");
                indent++;
                ranks.push(rank);
                closingTags.push(inputLine);

        }
        while (!closingTags.isEmpty()){
            String tag = closingTags.pop();
            indent --;
            printTag(output, indent,tag, "</%s>%n");
        }

        System.out.println(output);

    }

    private static void printTag(StringBuilder output, int indent, String tag, String format){

        for (int i = 0; i < indent; i++) {
            output.append(" ");
        }
        output.append(String.format(format,tag));

    }

}