#include <iostream> #include <algorithm> #include <iomanip> #include <vector> #include <queue> #include <deque> #include <set> #include <map> #include <tuple> #include <cmath> #include <numeric> #include <functional> #include <cassert> #include <atcoder/modint> #define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl; #define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl; template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } using namespace std; typedef long long ll; template<typename T> vector<vector<T>> vec2d(int n, int m, T v){ return vector<vector<T>>(n, vector<T>(m, v)); } template<typename T> vector<vector<vector<T>>> vec3d(int n, int m, int k, T v){ return vector<vector<vector<T>>>(n, vector<vector<T>>(m, vector<T>(k, v))); } template<typename T> void print_vector(vector<T> v, char delimiter=' '){ if(v.empty()) { cout << endl; return; } for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter; cout << v.back() << endl; } using mint = atcoder::modint998244353; ostream& operator<<(ostream& os, const mint& m){ os << m.val(); return os; } const ll MOD = 998244353; #define N_MAX 400002 mint inv[N_MAX],fac[N_MAX],finv[N_MAX]; void init(){ fac[0]=1;fac[1]=1; finv[0]=1;finv[1]=1; inv[1]=1; for(int i=2;i<N_MAX;i++){ inv[i]=mint(MOD)-inv[MOD%i]*(MOD/i); fac[i]=fac[i-1]*(ll) i; finv[i]=finv[i-1]*inv[i]; } } mint comb(ll n, ll r){ if(n < r){ return mint(0); }else{ return fac[n]*finv[r]*finv[n-r]; } } int main(){ ios::sync_with_stdio(false); cin.tie(0); cout << setprecision(10) << fixed; init(); int a, b; cin >> a >> b; cout << comb(a+b-2, a-1) << endl; }