バイナリハックイージー/unhappy Hacking (ABC Edit) (stack)

<span id="Label3"></p><p><p><span style="font-size: 15px;">Title Link: Http://abc043.contest.atcoder.jp/tasks/abc043_b</span></p></p><p><p><span class="lang lang-selected">Time limit:2sec/ <span class="lang lang-selected">Memory limit:256mb</span></span></p></p><p><p>Score: <var>200</var> points</p></p>Problem Statement<p><p>Sig has built his own Keyboard. Designed for Ultimate simplicity, This keyboard only have <var>3</var> keys on it:the <code>0</code> key, the <code>1</code> key and the backspace Key.</p></p><p><p>To begin with, The He is using a plain the text editor with the This Keyboard. This editor is always displays one string (possibly empty). Just after the editor was launched, this string is Empty. When all keys on the keyboard are pressed, the following changes occur to the String:</p></p> <ul> <ul> <li>The key:a letter would be inserted to the right of the <code>0</code> <code>0</code> string.</li> <li>The key:a letter would be inserted to the right of the <code>1</code> <code>1</code> string.</li> <li>The backspace key:if the string is empty and nothing happens. Otherwise, the rightmost letter of the string is Deleted.</li> </ul> </ul><p><p>Sig has launched the editor, and pressed these keys several times. You are given a string <var><em>s</em></var> , which was a record of his keystrokes in Order. In this string, the letter <code>0</code> stands <code>0</code> for the key, the letter <code>1</code> stands for the <code>1</code> key <code>B</code> and the letter Stands for the backspace key. What string is displayed in the editor now?</p></p>Constraints <ul> <ul> <li><var>1≦|<em>s</em>|≦10</var>( <var>|<em>s</em>|</var> denotes the length of <var><em>s</em></var> )</li> <li><var><em>s</em></var>Consists <code>0</code> of the letters, <code>1</code> and <code>B</code> .</li> <li>The correct answer is not a empty string.</li> </ul> </ul>