n, m = map(int, input().split())
a = [int(input()) for i in range(m)]

mod = 10**9+7
dp = [0] * (n+1)
dp[0] = 1

for i in range(1,n+1):
    if i in a:
        continue
    else:
        dp[i] = (dp[i-1] + dp[i-2]) % mod
print(dp[-1])