import numpy as np
N, M = map(int, input().split())
A = tuple([int(input()) for _ in range(M)])
MOD = 1000000007

dp = np.zeros(N + 2, dtype='int')
dp[0] = 1
for now in range(N):
    for _next in range(now + 1, now + 3):
        if _next not in A:
            dp[_next] += dp[now]
            dp[_next] %= MOD
print(dp[N])
