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;
typedef pair<int,int> P;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	ll N; cin >> N;
	map<ll,ll> mp;

	for (int i = 0;i < N;i++){
		ll A; cin >> A;
		mp[A]++;
	}
	
	ll l1 = 0;
	ll l2 = 0;

	for(auto&& i:mp){
		if(i.second >= 4){
			l1 = l2 = i.first;
		}
		else if(i.second >= 2){
			l2 = l1;
			l1 = i.first;
		}
	}

	cout << l1*l2 << endl;

	return 0;

}
