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

int main()
{
    ll a,b,c,d,e,f;
    cin>>a>>b>>c>>d>>e>>f;
    ll ans =pow((a+b+c),2)-(a*a)-(c*c)-(e*e);
    cout<<ans<<endl;
}