N, M = tuple(map(int, input().split()))
mod = 10**9+7
broken = []
dp = []

for i in range(M):
    broken.append(int(input()))

for i in range(N+1):
    dp.append(0)

dp[0] = 1

for i in range(1, N+1):
    if (i in broken):
        continue
    if (i == 1):
        dp[i] = 1
    dp[i] = (dp[i-1] + dp[i-2]) % mod

print(dp[N])