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 main(){
	long long n;
	cin>>n;
	map<long long,long long> x;
	for(long long i=0;i!=n;++i){
		long long temp;
		cin>>temp;
		++x[temp];
	}
	long long ans=1,br=0;
	for(auto it=x.rbegin();it!=x.rend();++it){
		while(br!=2 && it->second>=2){
			ans*=it->first;
			it->second-=2;
			++br;
		}
	}
	if(br==2)
		cout<<ans;
	else
		cout<<0;
}

