#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
using ll = long long;
using vl = vector<ll>;
const int mod = 998244353;

ll qpow(ll x, ll k)
{
    ll res = 1;
    while (k)
    {
        if (k & 1) res = res * x % mod;
        k >>= 1;
        x = x * x % mod;
    }
    return res;
}

void solve(void)
{
    int n, m;
    cin >> n >> m;
    int ans = 0;
    ans = qpow(m, n + 1);
    for (int x = 1; x < m; x ++) ans = (ans + mod - qpow(x, n)) % mod;
    ans = (ans + ans) % mod;
    ans = (ans + mod - qpow(m, n)) % mod;
    cout << ans << '\n';

}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int T = 1;
    // cin >> T;
    for (int i = 1; i <= T; i++)
    solve();

    return 0;
}