#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define pb push_back

typedef long long ll;
#define int ll

const int mod = 998244353;

int bpow(int a, int b)
{
    int r = 1;
    while (b > 0)
    {
        if (b%2 == 1)
            r = r*a%mod;
        a = a*a%mod;
        b /= 2;
    }
    return r;
}

int inv(int x)
{
    return bpow(x, mod-2);
}

const int N = 2e6+100;
int f[N];
int rf[N];

int cnk(int n, int k)
{
    return f[n] * rf[k] % mod * rf[n-k] % mod;
}

int dp[1000][1000];

int func(int n, int m)
{
    int ans = bpow(m, n);
    for (int m1=1; m1<=m; m1++)
    {
        int x = m-m1;
        int y = m1;
        ans += 2*bpow(x+y, n);
        ans -= 2*bpow(m1, n);
        ans %= mod;
        ans += mod;
        ans %= mod;
    }
    return ans;
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    f[0] = rf[0] = 1;
    for (int i=1; i<N; i++)
        f[i] = i*f[i-1]%mod;
    rf[N-1] = inv(f[N-1]);
    for (int i=N-2; i>=0; i--)
        rf[i] = rf[i+1]*(i+1)%mod;

//    for (int i=1; i<=100; i++)
//        for (int j=1; j<=100; j++)
//    {
//        int s = 2*bpow(j, i)-1;
//        for (int k=0; k<=i-1; k++)
//            s += cnk(i, k) * dp[i-k][j-1], s %= mod;
//        dp[i][j] = s%mod;
//    }
//
//    for (int i=1; i<=10; i++, cout<<"\n")
//        for (int j=1; j<=10; j++)
//            cout<<dp[i][j]<<" ";
//    return 0;

//    while (true)
    {
        int n, m;
        cin>>n>>m;
        cout<<func(n, m)<<endl;
    }

}