output_description: Print the number of ways to select cards such that the average of the written
  integers is exactly A.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      N A
      x_1 x_2 ... x_N
attempt: [n, a] = list(map(int, input().split()))
  xlist = list(map(int, input().split()))
  xlist.sort()
  for i in range(n):
      ave = a * i
      dp = [-1 for j in range(ave + 1)]
      dp[0] = 1
      for k in xlist:
          for l in range(len(xlist)):
              if dp[l] != -1 and l + k <= ave:
                  if dp[l + k] == -1:
                      dp[l + k] = 0
                  dp[l + k] += dp[l]
      ans += dp[-1]
  print(ans)
  
problem_description: Statement
  
  Tak has N cards. On the i-th (1 \leq i \leq N) card is written an integer x_i.
  He is selecting one or more cards from these N cards, so that the average of
  the integers written on the selected cards is exactly A. In how many ways can
  he make his selection?
samples: [{"input": "4 8\n    7 9 8 9", "output": "5\n    \n\n  * The following are the 5 ways to select cards such that the average is 8:\n    * Select the 3-rd card.\n    * Select the 1-st and 2-nd cards.\n    * Select the 1-st and 4-th cards.\n    * Select the 1-st, 2-nd and 3-rd cards.\n    * Select the 1-st, 3-rd and 4-th cards.\n\n* * *"}, {"input": "3 8\n    6 6 9", "output": "0\n    \n\n* * *"}, {"input": "8 5\n    3 6 2 8 7 6 5 9", "output": "19\n    \n\n* * *"}, {"input": "33 3\n    3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3", "output": "8589934591\n    \n\n  * The answer may not fit into a 32-bit integer."}]