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 N, A[100000];
vector<int> es;

int main(){
	cin >> N;
	for(int i = 0; i < N; ++i) cin >> A[i];
	sort(A, A + N);
	
	for(int i = 0; i < N - 1; ++i){
		if(A[i] == A[i+1]){
			es.push_back(A[i]);
			++i;
		}
	}
	
	if(es.size() >= 2){
		cout << 1LL*es[es.size()-2]*es[es.size()-1] << endl;
	}else{
		cout << 0 << endl;
	}
}