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;
typedef long long ll;

int main() {
	int N;  cin >> N;
	vector<ll> A(N);
	for (int i = 0; i < N; i++) cin >> A[i];
	sort(A.begin(), A.end());
	vector<ll> L;
	for (int i = N - 1; i >= 0; i--) {
		if (i >= 1 && A[i] == A[i - 1]) {
			L.push_back(A[i]);
			i--;
		}
	}
	if (L.size() < 2) {
		cout << 0 << endl;
		return 0;
	}

	cout << L[0] * L[1] << endl;
}
