#include #include using namespace std; using ll = long long; using pii = pair; using pll = pair; using vb = vector; using vi = vector; using vll = vector; using vvi = vector; using vvll = vector; using vpii = vector; using vpll = vector; using vs = vector; using vc = vector; #define rep(i, n) for (int i = 0; i < (int)(n); i++) #define all(a) (a).begin(), (a).end() #define uniq(v) sort(all(v)), (v).erase(unique(all(v)),(v).end()) #define lb(v,x) int(lower_bound(all(v),(x))-(v).begin()) #define ub(v,x) int(upper_bound(all(v),(x))-(v).begin()) #define rrep(i,n) for(int i = (int)(n) - 1; i>=0; i--) #define rep1(i,n) for(int i=1; i <=(int)(n);i++) #define reps(i,s,n) for(int i=(int)(s);i<(int)(n); i++) #define koz " " #define tor "\n" template using min_pq = priority_queue, greater>; template bool chmin(T& a, const T& b){if(b bool chmax(T& a, const T& b){if(a T ceil(T x, U y){ assert(y!=0); if(y<0) x=-x,y=-y; return (x>0 ? (x+y-1)/y : x/y); } template T floor(T x, U y){ assert(y!=0); if(y<0) x=-x,y=-y; return (x>0 ? x/y : (x-y+1)/y); } template int popcnt(T x){return __builtin_popcountll(x);} const int dx[]={1,0,-1,0,1,1,-1,-1}; const int dy[]={0,1,0,-1,1,-1,1,-1}; const int INF = 1045141919; const ll LINF = 3643648101145141919; const ll mod=998244353; const long long MOD = 998244353; const int MAX_C = 2000005; long long fact[MAX_C], inv_fact[MAX_C]; long long power(long long a, long long b, long long m) { long long res = 1; a %= m; while (b > 0) { if (b & 1) res = res * a % m; a = a * a % m; b >>= 1; } return res; } void init_comb() { fact[0] = 1; for (int i = 1; i < MAX_C; i++) fact[i] = fact[i-1] * i % MOD; inv_fact[MAX_C-1] = power(fact[MAX_C-1], MOD-2, MOD); for (int i = MAX_C-2; i >= 0; i--) { inv_fact[i] = inv_fact[i+1] * (i+1) % MOD; } } long long nCk(ll n, int k) { if (k < 0 || k > n) return 0; if(n> n; cout << nCk(n,2)*2%mod << tor; } int main() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(16); init_comb(); int _ = 1; //cin >> _; while(_--) solve(); }