output_description: Print the number of ways modulo $10^9+7$ in a line.
input_description: $n$ $k$
      
  
  The first line will contain two integers $n$ and $k$.
attempt: a, b = map(int, input().split())
  m = 10**9 + 7
  if a > b:
      print(0)
  else:
      r = 1
      for i in range(b - a + 1, b + 1):
          r *= i
          r %= m
      print(r)
  
problem_description: You have $n$ balls and $k$ boxes. You want to put these balls into the boxes.
  
  Find the number of ways to put the balls under the following conditions:
  
    * Each ball is distinguished from the other.
    * Each box is distinguished from the other.
    * Each ball can go into only one box and no one remains outside of the boxes.
    * Each box can contain at most one ball.
  
  Note that you must print this count modulo $10^9+7$.
samples: [{"input": "2 3", "output": "6"}, {"input": "3 2", "output": "0"}, {"input": "100 100", "output": "437918130"}]