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];

int main(){
	vector<int> len;
	scanf("%d", &N);
	for(int i = 0; i < N; i++) scanf("%d", &A[i]);
	sort(A, A + N, greater<int>());
	for(int i = 0; i < N - 1 && len.size() < 2; i++){
		if(A[i] == A[i + 1]) len.push_back(A[i]), i++;
	}
	if(len.size() == 2) printf("%lld\n", (long long)len[0] * len[1]);
	else printf("0\n");
	return 0;
}
