output_description: Print the number of ways to climb up the stairs under the condition, modulo 1\
  000\ 000\ 007.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N M
      a_1
      a_2
       .
       .
       .
      a_M
attempt: import sys
  
  sys.setrecursionlimit(10**7)
  INTMAX = 9223372036854775807
  INTMIN = -9223372036854775808
  MOD = 1000000007
  
  
  def POW(x, y):
      return pow(x, y, MOD)
  
  
  def INV(x, m=MOD):
      return pow(x, m - 2, m)
  
  
  def DIV(x, y, m=MOD):
      return (x * INV(y, m)) % m
  
  
  def LI():
      return [int(x) for x in input().split()]
  
  
  def LF():
      return [float(x) for x in input().split()]
  
  
  def LS():
      return input().split()
  
  
  def II():
      return int(input())
  
  
  N, M = LI()
  
  st = set()
  for i in range(M):
      st.add(int(input()))
  
  pat1 = 1
  pat2 = 0
  
  for i in range(1, N):
      tmp = pat2
      pat2 = pat1
      pat1 = ((pat1 + tmp) % MOD) if not i in st else 0
      # print('pat1: {} pat2: {} i:{}'.format(pat1, pat2, i))
  print((pat1 + pat2) % MOD)
  
problem_description: Statement
  
  There is a staircase with N steps. Takahashi is now standing at the foot of
  the stairs, that is, on the 0-th step. He can climb up one or two steps at a
  time.
  
  However, the treads of the a_1-th, a_2-th, a_3-th, \ldots, a_M-th steps are
  broken, so it is dangerous to set foot on those steps.
  
  How many are there to climb up to the top step, that is, the N-th step,
  without setting foot on the broken steps? Find the count modulo 1\ 000\ 000\
  007.
samples: [{"input": "6 1\n    3", "output": "4\n    \n\nThere are four ways to climb up the stairs, as follows:\n\n  * 0 \\to 1 \\to 2 \\to 4 \\to 5 \\to 6\n  * 0 \\to 1 \\to 2 \\to 4 \\to 6\n  * 0 \\to 2 \\to 4 \\to 5 \\to 6\n  * 0 \\to 2 \\to 4 \\to 6\n\n* * *"}, {"input": "10 2\n    4\n    5", "output": "0\n    \n\nThere may be no way to climb up the stairs without setting foot on the broken\nsteps.\n\n* * *"}, {"input": "100 5\n    1\n    23\n    45\n    67\n    89", "output": "608200469\n    \n\nBe sure to print the count modulo 1\\ 000\\ 000\\ 007."}]