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>
#define int long long
using namespace std;
const int N=100005;
int n;
int a[N];
int cnt[3],tot=0;
signed main(){
	scanf("%lld",&n);
	for(int i=1;i<=n;i++){
		scanf("%lld",&a[i]);
	}
	sort(a+1,a+n+1);
	for(int i=n;i>=1;i--){
		if(a[i]==a[i-1]){
			cnt[++tot]=a[i];
			i--;
			if(tot==2) break;
		}
	} 
	printf("%lld\n",cnt[1]*cnt[2]);
	exit(0);
}