n, m = map(int, input().split())
a = [int(input()) for i in range(m)]
dp = [0 for i in range(n + 1)]
dp[0] = 1
MOD = 10 ** 9 + 7
if a[0] > 1:
    dp[1] = 1
for i in range(2, n + 1):
    if i - 1 not in a:
        dp[i] += dp[i - 1]
    if i - 2 not in a:
        dp[i] += dp[i - 2]
    dp[i] %= MOD
print(dp[-1])
