#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 1000000 + 5;
const int P = 998244353;

int power(int a, int n) {
    int ans = 1;
    while (n) {
        if (n & 1) ans = 1ll * ans * a % P;
        a = 1ll * a * a % P; n >>= 1;
    }
    return ans;
}

int fac[MAX_N], ifac[MAX_N];

void init() {
    fac[0] = 1;
    for (int i = 1; i < MAX_N; i ++) fac[i] = 1ll * fac[i - 1] * i % P;
    ifac[MAX_N - 1] = power(fac[MAX_N - 1], P - 2);
    for (int i = MAX_N - 2; i >= 0; i --) ifac[i] = (i + 1ll) * ifac[i + 1] % P;
}

inline int Comb(int n, int m) {
    if (n < m || m < 0) return 0;
    return 1ll * fac[n] * ifac[m] % P * ifac[n - m] % P;
}

int main() {
    init();
    int N, M;
    cin >> N >> M;
    int ans = 0, x = power(M, N);
    for (int i = 1; i < M; i ++) {
        ans = (1ll * ans + x - power(i, N) + P) % P;
    }
    ans = (2ll * ans + x + P) % P;
    cout << ans << '\n';
    return 0;
}