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#4842. 矩形放置

통계

Grammy 有一個由 $W$ 條垂直線同 $H$ 條水平線組成嘅長方形格仔。佢想沿住啲格仔線畫兩個唔相交嘅長方形。其中一個長方形可以完全被另一個包住,但係兩個長方形唔可以有任何一點相交,包括邊界同角位。

請計算唔同嘅長方形畫法數目,模 $998\,244\,353$。兩幅畫被視為唔同,若且唯若有一條格仔邊界喺其中一幅畫有上色,而另一幅冇。

輸入

唯一一行包含兩個整數 $W$ 同 $H$ ($4 \leq W,H \leq 10^9$)。

輸出

輸出一個整數,表示唔同畫法嘅數目模 $998\,244\,353$。

例子

輸入 1

4 5

輸出 1

275

輸入 2

723435135 239873451

輸出 2

832099301

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