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

using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
const int MX = 1000010;
mint f[MX],inv[MX],fi[MX];
constexpr ll mod = 998244353;
void solve(){
    inv[1] = 1;
    for(int i=2;i<MX;i++){
        inv[i] = mod - (mod/i)*inv[mod%i];
    }
    f[0] = fi[0] = 1;
    for(int i=1;i<MX;i++){
        f[i] = f[i-1]*i;
        fi[i] = fi[i-1]*inv[i];
    }
}

mint nck(ll n, ll k){
    if(n<0 || k<0 || n<k) return 0;
    return f[n]*fi[k]*fi[n-k];
}

mint pw(mint a,ll x){
    mint ret = 1;
    while(x){
        if(x&1) (ret *= a);
        (a *= a); x /= 2;
    }
    return ret;
}

#include <atcoder/convolution>

using namespace std;
int main(){
    solve();
    int i,n,m; cin >> n >> m;
    vector<mint> F(n + 1),G(n + 1);
    for(i=0;i<=n;i++){
        mint val = pw(m + 1 - i,n)*fi[i];
        F[i] = i&1 ? -val : val;
    }
    for(i=0;i<=n;i++) G[i] = fi[i];
    vector<mint> H = convolution(F,G);
    mint ans = 0;
    for(i=1;i<=n;i++){
        ans += (2*i - 1)*f[i]*H[i];
    }
    cout << ans.val() << "\n";
    // for(i=1;i<=n;i++) cout << (H[i]*f[i]).val() << " ";
    // cout << "\n";
}