#include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long long ll; const int inf=1<<30; const ll INF=1LL<<62; typedef pair P; typedef pair PP; const ll MOD=998244353; const int mod = 998244353; struct mint { long long x; // typedef long long long long; mint(long long x=0):x((x%mod+mod)%mod){} mint operator-() const { return mint(-x);} mint& operator+=(const mint a) { if ((x += a.x) >= mod) x -= mod; return *this; } mint& operator-=(const mint a) { if ((x += mod-a.x) >= mod) x -= mod; return *this; } mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;} mint operator+(const mint a) const { return mint(*this) += a;}//後ろのconstはメンバxを変更しないことを示す mint operator-(const mint a) const { return mint(*this) -= a;} mint operator*(const mint a) const { return mint(*this) *= a;} bool operator==(const mint a) const {return a.x==x;} mint pow(unsigned long long int t) const { assert(t>=0); if (!t) return 1; //aがtで割り切れない場合には t%=(mod-1)をして良い mint a = pow(t>>1); a *= a; if (t&1) a *= *this; return a; } // for prime mod mint inv() const { return pow(mod-2);} mint& operator/=(const mint a) { return *this *= a.inv();} mint operator/(const mint a) const { return mint(*this) /= a;} }; std::istream& operator>>(std::istream& is, mint& a) { return is >> a.x;} std::ostream& operator<<(std::ostream& os, const mint& a) { return os << a.x;} struct combination { std::vector fact, ifact; combination(int n):fact(n+1),ifact(n+1) { assert(n < mod); fact[0] = 1; for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i; ifact[n] = fact[n].inv(); for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i; } mint operator()(int n, int K) { if (K < 0 || K > n) return 0; return fact[n]*ifact[K]*ifact[n-K]; } }; int main(){ ll N,M; cin>>N>>M; if(M==1){ cout<r) continue; mint add1=mint( (M-(l+1)*d) + (M-r*d) )*(r-l)/2; //cout<<"d="<