#include <iostream>
#include <atcoder/convolution>
#include <atcoder/modint>
#include <vector>

using namespace std;
using namespace atcoder;
typedef long long ll;
using mint = modint998244353;
vector<mint> g,h;
mint fac[200010];
mint pw(mint a,ll x){
    mint ret = 1;
    if(x==-1) return (mint)1/a;
    while(x){
        if(x&1) ret *= a;
        a *= a; x /= 2;
    }
    return ret;
}

mint f(int n,int m,int k){
    if(n - (k - 1)<0) return 0;
    if(m==k){
        if((n - (k - 1))==0) return 1;
        return 0;
    }
    return pw(m - k,2*n - 2*(k - 1));
}

int main(){
    int i,j,k,n,m; cin >> n >> m;
    fac[0] = 1;
    for(i=1;i<=200000;i++) fac[i] = fac[i - 1]*(mint)i;
    mint ans = pw(m,2*n + 1);
    g.resize(200001); h.resize(200001);
    for(j=0;j<=200000;j++) h[j] = (mint)1/fac[j];
    for(k=0;k<=n;k++) g[k] = f(n,m,k + 1)*pw(k + 1,k - 1)*pw(2,k)*fac[n]/(fac[n - k]*fac[k]);
    vector<mint> hg = convolution(h,g);
    for(i=0;i<m;i++) ans -= fac[i]*hg[i];
    cout << ans.val() << endl;
}