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