import numpy as np

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

ans = np.zeros(N + 1)
ans[N] = 1
broken_a = np.zeros(N)
for a_ in a:
    broken_a[a_] = 1
if broken_a[N-1] != 1:
    ans[N - 1] = 1


for i in range(2, N + 1):
    if broken_a[N - i] != 1:
        ans[N - i] = (ans[N - i + 1] + ans[N - i + 2])
    else:
        ans[N - i] = 0
print(int(ans[0] % (10 ** 9 + 7)))

