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 x,i,j,n,a[1<<17],p,q;
vector<int>v;
int main(){
  for(cin>>n;i<n;)cin>>a[i++];
  for(sort(a,a+n,greater<int>()),x=a[0],j=1;j<n;++j){
    if(x==a[j])v.push_back(a[j]),++j;
    x=a[j];
  }
  if(v.size()>1)cout<<(long long)v[0]*v[1]<<endl;
  else cout<<0<<endl;
}
