N, M = tuple(map(int, input().split()))
mod = 10**9+7
broken = [int(input()) for _ in range(M)]
dp = [0]* (N+1)


dp[0] = 1

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

print(dp[N])