当前你的浏览器版本过低，网站已在兼容模式下运行，兼容模式仅提供最小功能支持，网站样式可能显示不正常。
请尽快升级浏览器以体验网站在线编辑、在线运行等功能。
kcm1700, ntopia, suby, classic, tkwons, and their friends are having a birthday party for kcm1700. Of course, there is a very large birthday cake. They divide the birthday cake into undistinguishable pieces and put them on identical plates. kcm1700 is curious, so he wants to know how many ways there are to put m cake pieces on n plates.
In the only input line, there are two integers n, m (1 ≤ n, m ≤ 4 500), which are the number of the plates and the number of the cake pieces respectively.
If the number of ways is K, just output K mod 1000000007 because K can be very large.
3 7
8
There are 8 ways to fill 3 plates with 7 cakes, namely (0,0,7), (0,1,6), (0,2,5), (0,3,4), (1,1,5), (1,2,4), (1,3,3), (2,2,3).
| Case time limit(单组数据时间限制) | 1000MS |
| 时间上限 | 内存上限 |
| 5000 | 131072 |