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(){
	long long n, in;
	map<long long, long long> cnt;
	vector<long long> edge;
	cin >> n;
	
	for(long long i = 0 ; i < n ; i++){
		cin >> in;
		cnt[in]++;
		if(cnt[in] == 2){
			edge.push_back(in);
			cnt[in] = 0;
		}
	}
	
	sort(edge.begin(), edge.end(), greater<long long>());
	
	if(edge.size() < 2) cout << "0" << endl;
	else cout << (long long)edge[0]*edge[1] << endl;
	
	return 0;
}
