N,M = map(int,input().split())
A = [int(input()) for i in range(M)]

def recur(step):
  if step == N:
    return 1
  
  elif step in A or step > N:
    return 0
  
  else:
    ret1 = recur(step + 1) 
    ret2 = recur(step + 2) 
    return ret1 + ret2
    
print(recur(0) % (10 ** 9 + 7) )
    