N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
dp = [0] * (N+2)
dp[1] = 1
e = 1e9 + 7
for i in range(2, N+2):
    if i-1 not in A:
        dp[i] = (dp[i-1] + dp[i-2]) % e
print(int(dp[-1]))