output_description: Print the circumference of the circle. Your output is considered correct if
  and only if its absolute or relative error from our answer is at most 10^{-2}.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      R
attempt: n, k = map(int, input().split())
  m = 1000000007
  ans = []
  for i in range(1, n + 2):
      ans_min = (0 + (i - 1)) * i * 0.5
      ans_max = ((n + 1 - i) + n) * i * 0.5
      ans.append(ans_max - ans_min + 1)
  ans_wa = [ans[0]]
  for i in range(1, n + 1):
      ans_wa.append(ans_wa[i - 1] + ans[i])
  print(int((ans_wa[n] - ans_wa[k - 2]) % m))
  
problem_description: Statement
  
  Print the circumference of a circle of radius R.
samples: [{"input": "1", "output": "6.28318530717958623200\n    \n\nSince we accept an absolute or relative error of at most 10^{-2}, 6.28 is also\nan acceptable output, but 6 is not.\n\n* * *"}, {"input": "73", "output": "458.67252742410977361942"}]