要异或上一次输出的答案last_ans，初始时last_ans=0。</div>
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<p></p></div></div></div></div></div><div class="row"><div class="column"><h4 class="ui top attached block header">输出格式</h4><div class="ui bottom attached segment font-content"><div style="position: relative; overflow: hidden;"><div class=content><div>对于每个2操作，输出一个对应的答案。</div>
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