#!/usr/bin/env python3
import sys

sys.setrecursionlimit(1000000)

n, m, *a = map(int, open(0).read().split())
dp = [0] * (n + 1)
ok = [True] * (n + 1)

for i in a:
    ok[i] = False


def count(n):
    if n < 2:
        return 1
    if dp[n] != 0:
        return dp[n]
    dp[n] = (count(n - 1) * ok[n - 1] + count(n - 2) * ok[n - 2]) % (10**9 + 7)
    return dp[n]


print(count(n))
