#include <bits/stdc++.h>
using namespace std;
long long a[7];
int main() {
  for (int i = 0; i < 6; i++) scanf("%lld", 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];
  return 0;
}
