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 rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

int main(){
	int n,a[100000]; cin>>n;
	map<int,int> f;
	rep(i,n){
		int a; cin>>a;
		++f[a];
	}

	vector<int> b{0,0};
	for(auto x:f) if(x.second>=2) {
		while(x.second>=2){
			b.emplace_back(x.first);
			x.second-=2;
		}
	}

	sort(b.rbegin(),b.rend());
	cout<<1LL*b[0]*b[1]<<endl;

	return 0;
}
