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 n,a[100010];
int main(){
//	freopen("input.txt","r",stdin);// <--Remove Before Submit
	cin >>n;
	for(ll x=0;x<n;x++){
		cin >> a[x];
	}
	sort(a,a+n);
	ll d=1,n1=0,n2=0;
	for(ll x=n-1;x>=1;x--){
		if(a[x] == a[x-1]){
			d++;
			n2 = n1;
			n1 = a[x];
			a[x] = 0;
			a[x-1]=0;
		}
		if(n1!=0&&n2!=0){
			cout << n1*n2 << endl;
			return 0;
		}
	}
	cout << 0 << endl;
}