N, M = map(int, input().split())
a = [int(input()) for i in range(M)]
div = 1000000007

a.sort()
A = [0]*(N+1)
A[0] = 1

flag = True
for i in range(1, N+1):
  if flag and i == a[0]:
    A[i] = 0
    a.remove(i)
    if len(a)==0: flag = False
  else:
    if i==1: A[i] = 1
    else:
      A[i] = (A[i-1] + A[i-2])%div

print(A[N])