#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for (int i = 0; i < int(n); ++i)
using namespace std;
using namespace atcoder;
void fast_io(){cin.tie(0); ios::sync_with_stdio(0); cout<<fixed<<setprecision(20);}

using mint = modint998244353;

template<typename T>
struct Binom{
    Binom(int lim = 300000){ extend(lim); }
    static T fact(int x) {
        if (x < 0) return T(0);
        extend(x);
        return kaijo[x];
    }
    static T ifact(int x){
        if (x < 0) return T(0);
        extend(x);
        return kainv[x];
    }
    static T C(int n, int r){
        if (n < 0 || n < r || r < 0) return T(0);
        extend(n);
        return kaijo[n] * kainv[r] * kainv[n-r];
    }
    static T P(int n, int r){
        if (n < 0 || n < r || r < 0) return T(0);
        extend(n);
        return kaijo[n] * kainv[n-r];
    }
  private:
    static std::vector<T> kaijo, kainv;
    static void extend(int lim){
        int siz = kaijo.size();
        if (siz > lim) return ;
        int nsiz = siz * 2;
        kaijo.resize(nsiz+1), kainv.resize(nsiz+1);
        for (int i = siz; i <= nsiz; i++) kaijo[i] = kaijo[i-1] * T(i);
        kainv[nsiz] = kaijo[nsiz].inv();
        for (int i = nsiz-1; i >= siz; i--) kainv[i] = kainv[i+1] * T(i+1);
        extend(lim);
    }
};
template<typename T>
std::vector<T>Binom<T>::kaijo = vector<T>(2,T(1));
template<typename T>
std::vector<T>Binom<T>::kainv = vector<T>(2,T(1));


int main(){
    fast_io();
    int m, n; cin >> m >> n;
    vector<int> cnt(m,0);
    rep(i,n){
        int a; cin >> a;
        cnt[a-1]++;
    }
    vector<int> a(n+1,0);
    rep(i,m) a[cnt[i]]++;
    vector<pair<int,int>> b;
    rep(i,n+1) if (i > 0 && a[i] > 0) b.emplace_back(i,a[i]);
    Binom<mint> bnm;
    vector<mint> g(n+1,1);
    rep(k,n+1){
        for (auto p : b){
            g[k] *= (bnm.P(k,p.first)).pow(p.second);
        }
    } 
    vector<mint> xs(n+1,0), ys(n+1,0);
    rep(i,n+1){
        xs[i] = bnm.ifact(i) * (i % 2 == 0 ? 1 : -1);
        ys[i] = g[i] * bnm.ifact(i);
    }
    vector<mint> xy = convolution(xs,ys);
    mint ans = 0;
    rep(i,n+1) ans += xy[i] * bnm.fact(i);
    cout << ans.val() << endl;
}