CF468E Permanent

Little X has solved the #P-complete problem in polynomial time recently. So he gives this task to you. There is a special $ n×n $ matrix $ A $ , you should calculate its permanent modulo $ 1000000007 (10^{9}+7) $ . The special property of matrix $ A $ is almost all its elements equal to $ 1 $ . Only $ k $ elements have specified value. You can find the definition of permanent at the link: https://en.wikipedia.org/wiki/Permanent

The first line contains two space-separated integers $ n,k $ ( $ 1

Print the permanent of the matrix modulo $ 1000000007 (10^{9}+7) $ .