N, M = map(int, input().split())
oks = [True] * (N+1)
a = [int(input()) for _ in range(M)]
for i in a:
    oks[i] = False
dp = [0] * (N+1)
dp[0] = 1
for i in range(N+1):
    for j in range(i+1, min(i+2, N)+1):
        if oks[j]:
            dp[j] += int((dp[i]) % (1e9+7))


print(dp[N])