#include <bits/stdc++.h>
using namespace std;
inline long long int modadd(long long int n, long long int m,
                            long long int p = 998244353) {
  return ((n + m) % p + p) % p;
}
inline long long int modsub(long long int n, long long int m,
                            long long int p = 998244353) {
  return ((n - m + p) % p + p) % p;
}
inline long long int modpro(long long int n, long long int m,
                            long long int p = 998244353) {
  return (((n % p) * (m % p)) % p + p) % p;
}
unsigned long long int powe(long long int first, long long int second) {
  unsigned long long int res = 1;
  while (second > 0) {
    if (second & 1) res = res * first;
    second = second >> 1;
    first = first * first;
  }
  return res;
}
long long int modpow(long long int first, long long int second,
                     long long int p = 998244353) {
  long long int res = 1;
  while (second > 0) {
    if (second & 1) res = modpro(res, first, p);
    second = second >> 1;
    first = modpro(first, first, p);
  }
  return res;
}
inline long long int modInverse(long long int n, long long int p = 998244353) {
  if (n == 1) return 1;
  return modpow(n, p - 2, p);
}
inline long long int moddiv(long long int n, long long int m,
                            long long int p = 998244353) {
  return modpro(n, modInverse(m, p), p);
}
inline long long int modadd3(long long int first, long long int second,
                             long long int z, long long int p = 998244353) {
  return modadd(modadd(first, second, p), z, p);
}
inline long long int modadd4(long long int first, long long int second,
                             long long int z, long long int w,
                             long long int p = 998244353) {
  return modadd(modadd(first, second, p), modadd(z, w, p), p);
}
inline long long int modnCr(long long int fac[], int n, int r,
                            long long int p = 998244353) {
  if (r == 0) return 1;
  return modpro(fac[n], modInverse(modpro(fac[r], fac[n - r], p), p), p);
}
template <typename T>
inline T max3(T first, T second, T z) {
  return max(max(first, second), z);
}
template <typename T>
inline T max4(T first, T second, T z, T w) {
  return max(max3(first, second, w), z);
}
template <typename T>
inline T min3(T first, T second, T z) {
  return min(min(first, second), z);
}
template <typename T>
inline T min4(T first, T second, T z, T w) {
  return min(min3(first, second, w), z);
}
template <typename T>
void printArr(T *arr, int s, int n) {
  for (int i = s; i <= n; i++) {
    cout << arr[i] << " ";
  }
  cout << endl;
}
int main() {
  int erer = 1;
  for (int erer2 = (1); erer2 < (erer + 1); erer2++) {
    int a[6];
    cin >> a[0] >> a[1] >> a[2] >> a[3] >> a[4] >> a[5];
    cout << (a[0] + a[2] + a[1]) * (a[0] + a[2] + a[1]) - a[0] * a[0] -
                a[2] * a[2] - a[4] * a[4];
  }
  return 0;
}

### Prompt

Please provide a cpp coded solution to the problem described below:

Gerald got a very curious hexagon for his birthday. The boy found out that all the angles of the hexagon are equal to <image>. Then he measured the length of its sides, and found that each of them is equal to an integer number of centimeters. There the properties of the hexagon ended and Gerald decided to draw on it.

He painted a few lines, parallel to the sides of the hexagon. The lines split the hexagon into regular triangles with sides of 1 centimeter. Now Gerald wonders how many triangles he has got. But there were so many of them that Gerald lost the track of his counting. Help the boy count the triangles.

Input

The first and the single line of the input contains 6 space-separated integers a1, a2, a3, a4, a5 and a6 (1 ≤ ai ≤ 1000) — the lengths of the sides of the hexagons in centimeters in the clockwise order. It is guaranteed that the hexagon with the indicated properties and the exactly such sides exists.

Output

Print a single integer — the number of triangles with the sides of one 1 centimeter, into which the hexagon is split.

Examples

Input

1 1 1 1 1 1


Output

6


Input

1 2 1 2 1 2


Output

13

Note

This is what Gerald's hexagon looks like in the first sample:

<image>

And that's what it looks like in the second sample:

<image>

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
inline long long int modadd(long long int n, long long int m,
                            long long int p = 998244353) {
  return ((n + m) % p + p) % p;
}
inline long long int modsub(long long int n, long long int m,
                            long long int p = 998244353) {
  return ((n - m + p) % p + p) % p;
}
inline long long int modpro(long long int n, long long int m,
                            long long int p = 998244353) {
  return (((n % p) * (m % p)) % p + p) % p;
}
unsigned long long int powe(long long int first, long long int second) {
  unsigned long long int res = 1;
  while (second > 0) {
    if (second & 1) res = res * first;
    second = second >> 1;
    first = first * first;
  }
  return res;
}
long long int modpow(long long int first, long long int second,
                     long long int p = 998244353) {
  long long int res = 1;
  while (second > 0) {
    if (second & 1) res = modpro(res, first, p);
    second = second >> 1;
    first = modpro(first, first, p);
  }
  return res;
}
inline long long int modInverse(long long int n, long long int p = 998244353) {
  if (n == 1) return 1;
  return modpow(n, p - 2, p);
}
inline long long int moddiv(long long int n, long long int m,
                            long long int p = 998244353) {
  return modpro(n, modInverse(m, p), p);
}
inline long long int modadd3(long long int first, long long int second,
                             long long int z, long long int p = 998244353) {
  return modadd(modadd(first, second, p), z, p);
}
inline long long int modadd4(long long int first, long long int second,
                             long long int z, long long int w,
                             long long int p = 998244353) {
  return modadd(modadd(first, second, p), modadd(z, w, p), p);
}
inline long long int modnCr(long long int fac[], int n, int r,
                            long long int p = 998244353) {
  if (r == 0) return 1;
  return modpro(fac[n], modInverse(modpro(fac[r], fac[n - r], p), p), p);
}
template <typename T>
inline T max3(T first, T second, T z) {
  return max(max(first, second), z);
}
template <typename T>
inline T max4(T first, T second, T z, T w) {
  return max(max3(first, second, w), z);
}
template <typename T>
inline T min3(T first, T second, T z) {
  return min(min(first, second), z);
}
template <typename T>
inline T min4(T first, T second, T z, T w) {
  return min(min3(first, second, w), z);
}
template <typename T>
void printArr(T *arr, int s, int n) {
  for (int i = s; i <= n; i++) {
    cout << arr[i] << " ";
  }
  cout << endl;
}
int main() {
  int erer = 1;
  for (int erer2 = (1); erer2 < (erer + 1); erer2++) {
    int a[6];
    cin >> a[0] >> a[1] >> a[2] >> a[3] >> a[4] >> a[5];
    cout << (a[0] + a[2] + a[1]) * (a[0] + a[2] + a[1]) - a[0] * a[0] -
                a[2] * a[2] - a[4] * a[4];
  }
  return 0;
}

```