/**
	author:  shobonvip
	created: 2026.02.20 22:33:57
**/

#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)
#define all(v) v.begin(), v.end()

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

//defmodfact
const int COMinitMAX = 1145141;
mint fact[COMinitMAX+1], factinv[COMinitMAX+1];

void modfact(){
	fact[0] = 1;
	for (int i=1; i<=COMinitMAX; i++){
		fact[i] = fact[i-1] * i;
	}
	factinv[COMinitMAX] = fact[COMinitMAX].inv();
	for (int i=COMinitMAX-1; i>=0; i--){
		factinv[i] = factinv[i+1] * (i+1);
	}
}

mint cmb(int a, int b){
	if (a<b || b<0) return mint(0);
	return fact[a]*factinv[b]*factinv[a-b];
}
//--------


int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	modfact();
	
	int n, m;
	cin >> n >> m;
	vector<int> a(m);
	rep(i,0,m) cin >> a[i];
	vector<bool> exist(n+1);
	rep(i,0,m) {
		exist[a[i]] = true;
	}

	vector<mint> dp(n+1);
	auto calc = [&](auto self, int l, int r) -> void {
		if (l + 1 == r) {
			if (exist[l]) {
				dp[l] += fact[l];
			}
			return ;
		}
		int m = (l + r) / 2;
		
		self(self, l, m);

		vector<mint> f(r - l);
		vector<mint> g(m - l);
		rep(i,0,r-l) f[i] = fact[i+1];
		rep(i,0,m-l) g[i] = dp[i+l];

		vector<mint> conv = convolution(f, g);
		// shows, x^(m-l) -> m

		rep(i,0,r-m) {
			if (exist[i+m]) {
				dp[i+m] -= conv[i+m-l] * 2;
			}
		}

		self(self, m, r);
	};


	calc(calc, 1, n + 1);
	mint ans = 0;
	rep(i,0,n+1) {
		ans += fact[n-i] * (n-i+1) * dp[i];
	}
	ans = fact[n] - ans;
	cout << ans.val() << endl;
}