#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[6];
  for (int i = 0; i < 6; i++) {
    cin >> a[i];
  }
  cout << (a[0] + a[1] + a[2]) * (a[0] + a[1] + a[2]) - (a[0] * a[0]) -
              (a[2] * a[2]) - (a[4] * a[4])
       << endl;
}
