output_description: If it is not possible to untie all of the N-1 knots, print `Impossible`.
  
  If it is possible to untie all of the knots, print `Possible`, then print
  another N-1 lines that describe a possible order to untie the knots. The j-th
  of those N-1 lines should contain the index of the knot that is untied in the
  j-th operation. Here, the index of the knot connecting piece i and piece i+1
  is i.
  
  If there is more than one solution, output any.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      N L
      a_1 a_2 ... a_n
attempt: N, L = map(int, input().split())
  a = [map(int, input().split())]
  b = 0
  c = 0
  for i in range(N-1):
  	if a[i] + a[i+1] >= L:
  		print("Possible")
  		b = 1
  		c = i
  		break
  else:
  	print("Impossible")
  if b = 1:
  	for i in range(c+1):
  		print(i+1)
  	for i in range(N, c+1, -1):
  		print(i+1)
problem_description: Statement
  
  We have N pieces of ropes, numbered 1 through N. The length of piece i is a_i.
  
  At first, for each i (1≤i≤N-1), piece i and piece i+1 are tied at the ends,
  forming one long rope with N-1 knots. Snuke will try to untie all of the knots
  by performing the following operation repeatedly:
  
    * Choose a (connected) rope with a total length of at least L, then untie one of its knots.
  
  Is it possible to untie all of the N-1 knots by properly applying this
  operation? If the answer is positive, find one possible order to untie the
  knots.
samples: [{"input": "3 50\n    30 20 10", "output": "Possible\n    2\n    1\n    \n\nIf the knot 1 is untied first, the knot 2 will become impossible to untie.\n\n* * *"}, {"input": "2 21\n    10 10", "output": "Impossible\n    \n\n* * *"}, {"input": "5 50\n    10 20 30 40 50", "output": "Possible\n    1\n    2\n    3\n    4\n    \n\nAnother example of a possible solution is 3, 4, 1, 2."}]