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
// C - Make a Rectangle
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
#define allr(x) (x).rbegin(),(x).rend()
#define rp(i,s,e) for(int i=(s);i<(e);++i)

int main(){
	int N; cin>>N;
	vi A(N);
	rp(i, 0, N) cin>>A[i];
	sort(allr(A));
	vi ab(2);
	for(int c=0, i=0; i<N && c<2; ++i)
		if(A[i-1] == A[i]) ab[c++] = A[i++];
	cout<< (ll)ab[0]*ab[1] <<endl;
}