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;
typedef long long ll;
int main(){
  int n;cin>>n;
  vector<ll> a(n);
  for(int i=0;i<n;i++) cin>>a[i];
  sort(a.begin(),a.end(),greater<int>());
  int c=0;
  vector<ll> b={};
  for(int i=0;i<n-1;){
    if(a[i]==a[i+1]){
      b.push_back(a[i]);
      i+=2;
    }
    if(a[i]!=a[i+1]) i++;
    if(b.size()==2) break;
  }
  if(b.size()<=1) cout<<0<<endl;
  else cout<<b[0]*b[1]<<endl;
}
    