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>
#define ll long long 
using namespace std;
int main() {
	ll N;
	cin >> N;
	ll A[N];
	vector<ll> v;
	for (ll i = 0; i < N; i ++) {
		cin >> A[i];
	}
	sort(A, A + N);
	for (ll i = N - 2; i >= 0; i --) {
		if (A[i] == A[i + 1]) {
			v.push_back(A[i]);
			i --;
		} if (v.size() == 2) {
			cout << v[0] * v[1] << endl;
			return 0;
		}
	}
	cout << 0 << endl;
}