n, m = map(int, input().split())
a = []
mod = 10 ** 9 + 7
for _ in range(m):
    a.append(int(input()))
dp = [0] * (n + 1)
dp[0] = 1
dp[1] = 1
for i in range(2, n + 1):
    if i in a:
        continue
    else:
        dp[i] = dp[i - 1] + dp[i - 2]
print(dp[-1] % mod)
