#include <bits/stdc++.h>
using namespace std;
// #include <atcoder/modint>
// using namespace atcoder;
// using mint = modint998244353;
using ll = long long;
#define fix(x) fixed << setprecision(x)
#define rep(i, n) for(int i = 0; i < n; ++i)
#define all(x) (x).begin(),(x).end()
template<class T>bool chmin(T&a, const T&b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool chmax(T&a, const T&b){if(a<b){a=b;return 1;}return 0;}
constexpr ll INFLL = (1LL << 62), MOD = 998244353;
constexpr int INF = (1 << 30);

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll n,m;
    cin >> n >> m;
    ll ans = 0;
    if(n&1){
        if(n>2){
            ans = (n-3)*m;
            bool f = false;
            for(int i=30;i>=0;--i){
                if((m>>i)&1){
                    f = true;
                    ans += 1LL<<(i+1);
                    ans += ((1LL<<i)-1)*2;
                    break;
                }
            }
        }
    }else ans = n*m;
    cout << ans << '\n';
    return 0;
}