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瞬间移动

Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 3654    Accepted Submission(s): 1512


Problem Description
有一个无限大的矩形,初始时你在左上角(即第一行第一列),每次你都可以选择一个右下方格子,并瞬移过去(如从下图中的红色格子能直接瞬移到蓝色格子),求到第$n$行第$m$列的格子有几种方案,答案对$1000000007$取模。

 

Input
多组测试数据。

两个整数$n,m(2\leq n,m\leq 100000)$
 

Output
一个整数表示答案
 

Sample Input
4 5
 

Sample Output
10
 

Source
 

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