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;
ll sticks[100005];
ll best[100005];

int main(){
	int N;
	cin >> N;
	for(int a = 0; a < N; a++){
		cin >> sticks[a];
	}
	sort(sticks, sticks + N);
	int bestcnt = 0;
	for(int a = 0; a + 1 < N; a++){
		if(sticks[a] == sticks[a + 1]){
			best[bestcnt++] = sticks[a];
			a++;
		}
	}
	if(bestcnt < 2){
		cout << 0;
	} else {
		cout << best[bestcnt - 1] * best[bestcnt - 2];
	}
}