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()
{
	for(int n;cin>>n&&n;){
		vector<int> a(n);
		for(int& x:a) cin>>x;
		map<int,int> f;
		for(int x:a) f[x]++;

		vector<int> edges;
		for(int i=0;i<2;i++){
			int edge=0;
			for(auto p:f)
				if(p.second>=2)
					edge=p.first;
			edges.push_back(edge);
			f[edge]-=2;
		}
		cout<<(long long)edges[0]*edges[1]<<endl;
	}
}
