#include <bits/stdc++.h>

using i64 = long long;
constexpr i64 P = 998244353;

i64 norm(i64 a) {
    a %= P;
    if (a < 0) a += P;
    return a;
}

i64 modpow(i64 a, i64 e) {
    i64 r = 1;
    a = norm(a);
    while (e > 0) {
        if (e & 1) r = r * a % P;
        a = a * a % P;
        e >>= 1;
    }
    return r;
}

i64 quotient(i64 a, i64 b) {
    return norm(a) * modpow(b, P - 2) % P;
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    i64 N, M;
    std::cin >> N >> M;
    if (norm(M + 1) == 0) {
        std::cout << norm((N & 1) ? N - 1 : -(N - 1)) << '\n';
        return 0;
    }
    i64 numerator = norm(modpow(M, N % (P - 1)) + (N & 1 ? -norm(M) : norm(M)));
    std::cout << quotient(numerator, M + 1) << '\n';
    return 0;
}