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

mod = 10**9 + 7
dp = [0] * (n+1)
dp[0] = 1
if 1 not in a:
    dp[1] = 1
if 2 not in a:
    dp[2] = dp[0] + dp[1]
for i in range(3, n+1):
    if i not in a:
        dp[i] = (dp[i-1] + dp[i-2]) % mod
print(dp[n] % mod)
        