output_description: Print the number of patties in the bottom-most X layers from the bottom of a
  level-N burger.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N X
attempt: n, x = (int(x) for x in input().split())
  
  f = [0] * (n + 1)
  g = [0] * (n + 1)
  f[0] = 1
  g[0] = 1
  for i in range(1, n + 1):
      f[i] = f[i - 1] * 2 + 3
      g[i] = g[i - 1] * 2 + 1
  
  total = 0
  remain = x
  
  
  def eat(n):
  
      global total
      global f
      global remain
  
      if remain == 0:
          return
      if f[n] <= remain:
          total += g[n]
          remain -= f[n]
          return
      if f[n] > remain:
          remain -= 1
          if f[n - 1] > remain:
              eat(n - 1)
          else:
              total += g[n - 1]
              remain -= f[n - 1]
              total += 1
              remain -= 1
              eat(n - 1)
  
  
  eat(n)
  print(total)
  
problem_description: Statement
  
  In some other world, today is Christmas.
  
  Mr. Takaha decides to make a multi-dimensional burger in his party. A _level-
  L burger_ (L is an integer greater than or equal to 0) is the following thing:
  
    * A level-0 burger is a patty.
    * A level-L burger (L \geq 1) is a bun, a level-(L-1) burger, a patty, another level-(L-1) burger and another bun, stacked vertically in this order from the bottom.
  
  For example, a level-1 burger and a level-2 burger look like `BPPPB` and
  `BBPPPBPBPPPBB` (rotated 90 degrees), where `B` and `P` stands for a bun and a
  patty.
  
  The burger Mr. Takaha will make is a level-N burger. Lunlun the Dachshund will
  eat X layers from the bottom of this burger (a layer is a patty or a bun). How
  many patties will she eat?
samples: [{"input": "2 7", "output": "4\n    \n\nThere are 4 patties in the bottom-most 7 layers of a level-2 burger\n(`BBPPPBPBPPPBB`).\n\n* * *"}, {"input": "1 1", "output": "0\n    \n\nThe bottom-most layer of a level-1 burger is a bun.\n\n* * *"}, {"input": "50 4321098765432109", "output": "2160549382716056\n    \n\nA level-50 burger is rather thick, to the extent that the number of its layers\ndoes not fit into a 32-bit integer."}]