#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define ll long long

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int N, M;
    cin >> N >> M;
    vector<vector<mint>> dp(N+1, vector<mint>(N+1, 0));
    dp[0][0] = 1;
    for (int i=0;i<N;i++) {
        for (int j=0;j<=N;j++) {
            if (j == 0) {
                dp[i+1][1] += dp[i][j]*(M-1);
            } else {
                dp[i+1][1] += dp[i][j]*(M-2);
            }
            if (j+1 <= N && M-j > 0 && j > 0) dp[i+1][j+1] += dp[i][j]*(mint(M-j).inv())*(M-j-1);
        }
    }

    cout << "dp: " << "\n";
    for (int i=0;i<=N;i++) {
        for (int j=0;j<=N;j++) {
            cout << dp[i][j].val() << " ";
        }
        cout << "\n";
    }

    mint ans = mint(M).pow(N);
    // cout << ans.val() << "\n";
    for (int i=0;i<=N;i++) ans -= dp[N][i];
    cout << ans.val() << "\n";
    return 0;
}