//
//  main.cpp
//  qq
//
//  Created by apple on 15/11/1.
//  Copyright (c) 2015年 刘泽群. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#define mod 998244353
#define maxn 110000
using namespace std;
typedef long long ll;
ll a[maxn];
int main() {
    freopen("tria.in", "r", stdin);
    freopen("tria.out", "w", stdout);
    ll n,m;
    cin>>n>>m;
    a[3]=1;
    for (int i=3; i<=n; i++) {
        a[i+1]=a[i]+(i%mod)*((i-1)%mod)/2;
        a[i+1]%=mod;
    }
    ll ans=a[n]+n*(n-1)/2;
    cout<<ans;
        return 0;
}