#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define int ll
void solve()
{
    int n,m;
    cin>>n>>m;
    if(n==1||m==1){
        if(n==1){
            int base=m/4*14;
            if(m%4==0){
                base+=0;
            }
            else if(m%4==1){
                base+=3;
            }
            else if(m%4==2){
                base+=5;
            }
            else{
                base+=9;
            }
            cout<<base<<'\n';
        }
        else{
            int base=m/4*14;
            if(n%4==0){
                base+=0;
            }
            else if(n%4==1){
                base+=3;
            }
            else if(n%4==2){
                base+=4;
            }
            else{
                base+=8;
            }
            cout<<base<<'\n';
        }

    }
    else{
        cout<<n*m*6<<'\n';
    }
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int t=1;
    //cin >> t;
    while (t--)
    {
        solve();
    }
}