output_description: Print the number of pairs of integers (x, y) (L \leq x \leq y \leq R)
  satisfying the condition, modulo 10^9 + 7.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      L R
attempt: import collections, bisect
  
  s = input()
  t = input()
  
  n = len(s)
  d = collections.defaultdict(list)
  for i, c in enumerate(s):
      d[c].append(i + 1)
  
  m = len(t)
  x = [0] * (m + 1)  # 長さを記録
  y = [0] * (m + 1)  # 添え字を記録
  
  for i in range(1, m + 1):
      c = t[i - 1]
      if not c in d:
          print(-1)
          exit()
  
      a = y[i - 1]
      ptr = bisect.bisect_right(d[c], y[i - 1])
      if ptr == len(d[c]):
          b = d[c][0]
      else:
          b = d[c][ptr]
  
      y[i] = b
      if a < b:
          x[i] = x[i - 1] + b - a
      else:
          x[i] = x[i - 1] + n - a + b
  
  print(x[-1])
  
problem_description: Statement
  
  Given are integers L and R. Find the number, modulo 10^9 + 7, of pairs of
  integers (x, y) (L \leq x \leq y \leq R) such that the remainder when y is
  divided by x is equal to y \mbox{ XOR } x.
  
  What is \mbox{ XOR }?
  
  The XOR of integers A and B, A \mbox{ XOR } B, is defined as follows:
  
    * When A \mbox{ XOR } B is written in base two, the digit in the 2^k's place (k \geq 0) is 1 if either A or B, but not both, has 1 in the 2^k's place, and 0 otherwise.
  
  For example, 3 \mbox{ XOR } 5 = 6. (In base two: 011 \mbox{ XOR } 101 = 110.)
samples: [{"input": "2 3", "output": "3\n    \n\nThree pairs satisfy the condition: (2, 2), (2, 3), and (3, 3).\n\n* * *"}, {"input": "10 100", "output": "604\n    \n\n* * *"}, {"input": "1 1000000000000000000", "output": "68038601\n    \n\nBe sure to compute the number modulo 10^9 + 7."}]