АПС Лаб 4 Модифициран XML код

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.NoSuchElementException;
import java.io.BufferedReader;
import java.io.*;


import java.io.InputStreamReader;


import java.text.ParseException;


import java.util.NoSuchElementException;


interface Stack<E> {


    public boolean isEmpty ();


    public E peek ();


    public void clear ();


    public void push (E x);


    public E pop ();

}

 class ArrayStack<E> implements Stack<E> {


    private E[] elems;
    private int depth;

    @SuppressWarnings("unchecked")
    public ArrayStack (int maxDepth) {

        elems = (E[]) new Object[maxDepth];
        depth = 0;
    }


    public boolean isEmpty () {

        return (depth == 0);
    }


    public E peek () {

        if (depth == 0)
            throw new NoSuchElementException();
        return elems[depth-1];
    }


    public void clear () {

        for (int i = 0; i < depth; i++)  elems[i] = null;
        depth = 0;
    }


    public void push (E x) {
        elems[depth++] = x;
    }


    public E pop () {
        if (depth == 0)
            throw new NoSuchElementException();
        E topmost = elems[--depth];
        elems[depth] = null;
        return topmost;
    }
}


public class CheckXML {

    public static void main(String[] args) throws Exception{

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        int n = Integer.parseInt(s);
        String [] redovi = new String[n];

        for(int i=0;i<n;i++)
            redovi[i] = br.readLine();

        int valid=1;
        ArrayStack<String> nov=new ArrayStack<String>(n);
        String st=new String();
        String novs=new String();
        for(int j=0;j<n;j++){
            int dolzina=redovi[j].length();
            st=redovi[j].substring(0,2);

            if(st.equals("[/"))
            {
                novs=nov.pop();
                int dolzina1=novs.length();
                if(!(redovi[j].substring(2,dolzina-1).equals(novs.substring(1,dolzina1-1)))){
                valid=0;
                    j=n;
                }
            }
            else{
                st=redovi[j].substring(0,1);
                if(st.equals("[")){
                nov.push(redovi[j]);
                }
            }
        }
        System.out.println(valid);

        br.close();
    }
}