MOD = 10 ** 9 + 7
N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
dp = [0] * (N + 1)
dp[0] = 1
for i in range(1, N + 1):
    if i in A:
        dp[i] = 0
    else:
        dp[i] = (dp[i - 2] + dp[i - 1]) % MOD
print(dp[N])