#include <bits/stdc++.h>
using namespace std;
const long long MOD = 998244353;
int main(){
  int N, M;
  cin >> N >> M;
  vector<vector<long long>> dp(N + 1, vector<long long>(M + 1, 0));
  for (int i = 1; i <= M; i++){
    for (int j = 1; j < i; j++){
      if (j <= N){
        dp[j][i]++;
      }
    }
  }
  vector<vector<long long>> dpsum(N + 2, vector<long long>(M + 1, 0));
  vector<long long> sum(N + 2, 0);
  for (int i = 1; i <= N; i++){
    sum[i + 1] = sum[i];
    for (int j = 1; j <= M; j++){
      dpsum[i + 1][j] = dpsum[i][j];
      int k = max(i - j + 1, 0);
      dp[i][j] += sum[i] - sum[k] + MOD;
      dp[i][j] -= dpsum[i][j] - dpsum[k][j];
      dp[i][j] += MOD;
      dp[i][j] %= MOD;
      sum[i + 1] += dp[i][j];
      sum[i + 1] %= MOD;
      dpsum[i + 1][j] += dp[i][j];
      dpsum[i + 1][j] %= MOD;
    }
  }
  long long ans = 1;
  for (int i = 0; i < N; i++){
    ans *= M;
    ans %= MOD;
  }
  for (int i = 1; i <= M; i++){
    ans += MOD - dp[N][i];
    ans %= MOD;
  }
  cout << ans << endl;
}