#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n, m;
    cin >> n >> m;
    if(n % 2 == 0){
        cout << n * m << '\n';
        return 0;
    }
    ll g = 1ll << __lg(m) + 1;
    g--;
    cout << (n - 1) * (g + m) / 2 << '\n';
}