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 + 2 in A:
        dp[i + 2] = 0
    elif i + 2 == 1:
        dp[i + 2] = dp[i + 1]
    else:
        dp[i + 2] = (dp[i + 1] + dp[i]) % (10 ** 9 + 7)
        
print(dp[-1])