#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
void solve(){
  ll n, m;
  cin >> n >> m;
  if(n != 1 && m != 1){
    cout << n * m * 6 << '\n';
  }
  vector<int> v(4);
  if(n == 1){
    int num = m / 4;
    int cur = m % 4;
    v[1] = 6;
    v[2] = 9;
    v[3] = 10;
    cout << num * 14 + v[cur] << '\n';
  }
  else if(m == 1){
    int num = n / 4;
    int cur = n % 4;
    v[1] = 6;
    v[2] = 8;
    v[3] = 9;
    cout << num * 14 + v[cur] << '\n';
  }
}

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int t = 1;
  // cin >> t;
  while(t--){
    solve();
  }
}