#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;

typedef long long ll;
//typedef modint1000000007 mint;
const int MOD = 998244353;
#define all(x) x.begin(), x.end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
const int inf = 1 << 30;
const ll INF = 1LL << 60;
const int dx[8] = {1, 0, -1, 0, -1, -1, 1, 1};
const int dy[8] = {0, 1, 0, -1, -1, 1, -1, 1};
template <class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; }
template <class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }

//a ^ n % modを計算する(O(logN))
ll modpow(ll a, ll n, ll mod){
    ll res = 1;
    while(n > 0){
        if(n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

int main(){
    int n, m;
    cin >> n >> m;

    if(n < m){
        cout << 0 << endl;
        return 0;
    }

    int ans = modpow(2, n, MOD) - modpow(2, m - 1, MOD);
    ans %= MOD;
    ans += MOD;
    ans %= MOD;

    cout << ans << endl;

    return 0;
}