#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001

struct combi{
	deque<mint> kaijou;
	deque<mint> kaijou_;
	
	combi(int n){
		kaijou.push_back(1);
		for(int i=1;i<=n;i++){
			kaijou.push_back(kaijou[i-1]*i);
		}
		
		mint b=kaijou[n].inv();
		
		kaijou_.push_front(b);
		for(int i=1;i<=n;i++){
			int k=n+1-i;
			kaijou_.push_front(kaijou_[0]*k);
		}
	}
	
	mint combination(int n,int r){
		if(r>n)return 0;
		mint a = kaijou[n]*kaijou_[r];
		a *= kaijou_[n-r];
		return a;
	}
	
	mint junretsu(int a,int b){
		mint x = kaijou_[a]*kaijou_[b];
		x *= kaijou[a+b];
		return x;
	}
	
	mint catalan(int n){
		return combination(2*n,n)/(n+1);
	}
	
};

int main(){
	
	int n,m;
	cin>>n>>m;
	
	combi C(100000);
	
	vector<mint> dp(n+1,0);
	dp[0] = 1;
	mint ans = 0;
	for(int i=1;i<=n+3;i++){
		if(i-1>m)break;
		rep(j,dp.size()){
			dp[j] *= C.kaijou_[j];
		}
		vector<mint> tdp(n+1,0);
		rep(j,n+1){
			if(j==0)continue;
			tdp[j] = C.kaijou_[j];
		}
		dp = convolution(dp,tdp);
		while(dp.size()>n+1)dp.pop_back();
		rep(j,dp.size())dp[j] *= C.kaijou[j];
		
		int tt = m+1;
		tt += max(0, m-(i+1)+1);
		rep(j,dp.size()){
			mint x = dp[j];
			x *= C.combination(n,j);
			x *= mint(tt).pow(n-j);
			x *= i;
			ans += x;
		}
	}
	cout<<ans.val()<<endl;
	
	return 0;
}