=10**9+7
n,m=map(int,input().split())
A=[1 for i in range(n)]
if n!=1:
  A[1]=2
  for i in range(m):
    A[int(input())-1]=0
  
  if A[0]==0 and A[1]!=0:
    A[1]=1



  for i in range(2,n):
    if A[i]!=0:
      A[i]=(A[i-1]+A[i-2])
      A[i]%=MOD

    
  print(A[n-1])