#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)n;i++)
typedef int64_t ll;


int main() {
	int N, M;
	cin >> N >> M;

	vector<int> oks(N + 1, true);
	for (int i = 0; i < M; i++)
	{
		int a; cin >> a;
		oks[a] = false;
	}

	vector<ll> dp(N + 1);
	dp[0] = 1;
	for (int now = 0; now < N; ++now) {
		for (int next = now+1;  next <= min(N,now+2);  next++)
		{
			if (oks[next])
			{
				dp[next] += dp[now];
				dp[next] %= mod;
			}
		}
	}
	cout << dp[N] << endl;
	return 0;
}
