// 入栈后栈仍保持单调递增（因为小的都被弹走了）
Медведев вышел в финал турнира в Дубае17:59
。下载安装 谷歌浏览器 开启极速安全的 上网之旅。是该领域的重要参考
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There is a special form for boolean formulas called "Conjunctive Normal Form" (CNF). A problem in this form consists of clauses connected with and operators, where each clause only contains variables connected with or operators. The variables can appear negated, but only variables can be directly negated, something like !(a && b) is not allowed. An example boolean formula in CNF form is: