mod = 10**9+7
N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]

dp = [0] * (N + 1)
dp[:2] = 1, 1 if 1 not in a else 0

for i in range(2, N+1):
    if not i in a:
        dp[i] = (dp[i-1] + dp[i-2]) % mod
print(dp[-1])
