#include <bits/stdc++.h>

#define FOR(i, x, n) for(int i = x; i < n; i++)
#define F0R(i, n) FOR(i, 0, n)

#define F first
#define S second

#define IOS ios_base::sync_with_stdio(0); cin.tie(0);

using namespace std;

typedef long long LL;

const int N = 1e6 + 7;
const int INF = 1e9 + 7;
const int MOD = 998'244'353;

LL pw(LL a, LL b) {
    LL ret = 1;
    while(b) {
        if (b & 1) ret = ret * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }

    return ret;
}

int main() {
    IOS;

    int n, m;
    cin >> n >> m;

    LL ans = pw(m, n + 1);

    FOR(i, 1, m) ans = (ans - pw(i, n) + MOD) % MOD;
    ans = (ans - pw(m, n) + MOD) % MOD;
    ans = (ans << 1) % MOD;
    ans = (ans + pw(m, n)) % MOD;

    cout << (ans + MOD) % MOD;
}