#line 1 "Main.cpp" #include #include #include #include #include #include #line 3 "nachia\\math\\combination.hpp" namespace nachia{ template class Comb{ private: std::vector F; std::vector iF; public: void extend(int newN){ int prevN = (int)F.size() - 1; if(prevN >= newN) return; F.resize(newN+1); iF.resize(newN+1); for(int i=prevN+1; i<=newN; i++) F[i] = F[i-1] * Modint::raw(i); iF[newN] = F[newN].inv(); for(int i=newN; i>prevN; i--) iF[i-1] = iF[i] * Modint::raw(i); } Comb(int n = 1){ F.assign(2, Modint(1)); iF.assign(2, Modint(1)); extend(n); } Modint factorial(int n) const { return F[n]; } Modint invFactorial(int n) const { return iF[n]; } Modint invOf(int n) const { return iF[n] * F[n-1]; } Modint comb(int n, int r) const { if(n < 0 || n < r || r < 0) return Modint(0); return F[n] * iF[r] * iF[n-r]; } Modint invComb(int n, int r) const { if(n < 0 || n < r || r < 0) return Modint(0); return iF[n] * F[r] * F[n-r]; } Modint perm(int n, int r) const { if(n < 0 || n < r || r < 0) return Modint(0); return F[n] * iF[n-r]; } Modint invPerm(int n, int r) const { if(n < 0 || n < r || r < 0) return Modint(0); return iF[n] * F[n-r]; } Modint operator()(int n, int r) const { return comb(n,r); } }; } // namespace nachia #line 8 "Main.cpp" using namespace std; using i32 = int32_t; using u32 = uint32_t; using i64 = int64_t; using u64 = uint64_t; #define rep(i,n) for(int i=0; i<(int)(n); i++) const i64 INF = 1001001001001001001; using Modint = atcoder::modint998244353; int main(){ int N, M; cin >> N >> M; auto C = nachia::Comb(N+M); Modint ans = C.factorial(M); for(int i=0; i