#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <map>

using namespace std;
using ll = long long;

const int mod = 998244353;

int lgput(int x, int p) {
    if (p == 0) {
        return 1;
    }
    if (p % 2 == 0) {
        int k = lgput(x, p/2);
        return 1LL * k * k % mod;
    }
    else {
        int k = lgput(x, p - 1);
        return 1LL * k * x % mod;
    }
}

void solve() {
    int n, m;
    cin >> n >> m;
    vector <int> drd(n + 5);
    ll prost = 0, ans = 0;
    for (int i = 1; i <= (n-1)/2; i++) {
        int cnt = lgput(m, i);
        prost *= m;
        prost %= mod;
        if (i % 2 == 0) {
            prost += drd[i/2];
            prost %= mod;
        }
        cnt -= prost;
        if (cnt < 0) {
            cnt += mod;
        }
        drd[i] = cnt;
        //cerr << i << ' ';
        //cerr << drd[i] << '\n';
        int add = 1LL * drd[i] * lgput(m, n - 2 * i) % mod;
        ans += add;
        ans %= mod;
    }
    cout << ans;
}

signed main() {
#ifdef LOCAL
    freopen("test.in", "r", stdin);
    freopen("test.out", "w", stdout);
#endif // LOCAL
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int nrt = 1;
    //cin >> nrt;
    while (nrt--) {
        solve();
    }
    return 0;
}