//#include <monsterenergy>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int MAX = 1e9;
const int MIN = -1*1e9;
const ll MAXLL = 1e18;
const ll MINLL = -1*1e18;

int main()
{
    ll N,M; cin >> N >> M;
    if(N%2 == 0)
    {
        cout << N*M << endl;
        return 0;
    }
    
    ll Ans = (N-1)*M;
    for(ll i = 0; i < 60; i++) {
        if((1LL<<i) <= M && (!(M&(1LL<<i)))) Ans += (1LL<<i)*2;
    }
    cout << Ans << endl;
    return 0;
}