#include <bits/stdc++.h>
using namespace std;
int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
int a[7];
int main() {
  int i, j;
  for (i = 1; i <= 6; i++) a[i] = read();
  int ans = a[1] + a[2] + a[3];
  ans = ans * ans;
  ans = ans - a[1] * a[1] - a[3] * a[3] - a[5] * a[5];
  printf("%d\n", ans);
  return 0;
}
