We have N sticks with negligible thickness. The length of the i-th stick is A_i.

Snuke wants to select four different sticks from these sticks and form a rectangle (including a square), using the sticks as its sides. Find the maximum possible area of the rectangle.

Constraints

* 4 \leq N \leq 10^5
* 1 \leq A_i \leq 10^9
* A_i is an integer.

Input

Input is given from Standard Input in the following format:


N
A_1 A_2 ... A_N


Output

Print the maximum possible area of the rectangle. If no rectangle can be formed, print 0.

Examples

Input

6
3 1 2 4 2 1


Output

2


Input

4
1 2 3 4


Output

0


Input

10
3 3 3 3 4 4 4 5 5 5


Output

20
#include <bits/stdc++.h>
using namespace std;

int main()
{
    int n;
    cin >> n;

    vector<int> a(n + 2);
    for (int i = 0; i < n; i++) cin >> a[i];

    sort(a.rbegin(), a.rend());

    vector<int> t;
    for (int i = 1; i < a.size(); i++) {
        if (a[i] == a[i - 1]) {
            t.push_back(a[i++]);
        }
    }
    cout << 1LL * t[0] * t[1] << endl;

    return 0;
}
