#include <bits/stdc++.h>
#include <atcoder/all>

using namespace std;
using namespace atcoder;

typedef long long ll;
using mint = modint998244353;

// Calculate sum of geometric sequence: s + sr + sr^2 + ... + sr^{N-1}
mint sum_of_geometric_sequence(mint s, mint r, ll N) {
    if (r == 1) return s * N;
    return s * (r.pow(N) - 1) / (r - 1);
}

int main() {
    ll N, M;
    cin >> N >> M;

    mint ans = 0;
    for (int c = 1; c <= M; c++) {
        mint r = (mint)c / (mint)M;
        ans += sum_of_geometric_sequence(r, r, N);
    }

    ans *= ((mint)M).pow(N);
    cout << ans.val() << endl;
}