#include<bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
typedef long long ll;
#define rep(i,n) for(ll i=0, i##_len=(n); i<i##_len; ++i)
#define REP(i,num,n) for(ll i=num, i##_len=(n); i<i##_len; ++i)
#define repprev(i,a,b) for(ll i=b-1;i>=a;i--)
#define reprev(i,n) repprev(i,0,n)
using namespace std;
#define sz(x) ((int)(x).size())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
#define MEMSET(v, h) memset((v), h, sizeof(v))
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<class T> int former(const vector<T> &v, T x){
   return upper_bound(v.begin(),v.end(),x) - v.begin() - 1;
}
template<class T> int latter(const vector<T> &v, T x){
    return lower_bound(v.begin(),v.end(),x) - v.begin();
}
#define pb push_back
#define mp make_pair
#define y0 y3487465
#define y1 y8687969
#define j0 j1347829
#define j1 j234892
#define BIT_FLAG_0 (1<<0) // 0000 0000 0000 0001
#define BIT_FLAG_1 (1<<1) // 0000 0000 0000 0010
#define BIT_FLAG_2 (1<<2) // 0000 0000 0000 0100
#define BIT_FLAG_3 (1<<3) // 0000 0000 0000 1000
#define BIT_FLAG_4 (1<<4) // 0000 0000 0001 0000
#define BIT_FLAG_5 (1<<5) // 0000 0000 0010 0000
#define BIT_FLAG_6 (1<<6) // 0000 0000 0100 0000
#define BIT_FLAG_7 (1<<7) // 0000 0000 1000 0000
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
const ll LLINF = 1LL<<60;
const int INF = 1<<29;

const int MAX = 510000;
const int MOD = 1000000007;



const int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
const int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};


ll binary_search(){
	while(abs(ok - ng) > 1){
		ll mid = (ok + ng) / 2;
		if(solve(mid))
		{
			ok = mid;
		}else{
			ng = mid;
		}
	}
}

ll dp[100100];

int main(void) {
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll n, m;
	cin >> n >> m;
	vector<ll> a(m);
	rep(i,m) {
		cin >> a[i];
		dp[a[i]] = -1;
	}
	dp[0] = 1;
	rep(i,n) {
		if(dp[i] == -1) continue;
		if(dp[i + 1] != -1) {
			dp[i + 1] = max(dp[i + 1], dp[i] + 1);
			dp[i + 1] %= MOD;
		}
		if(dp[i + 2] != -1){
		 dp[i + 2] = max(dp[i + 2], dp[i] + 1);
		 dp[i + 2] %= MOD;
		}
	}
	cout << dp[n] << endl;
	
}
