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;
typedef pair<int,int> P;
#define rep(i,m,n) for(int i=m;i<n;i++)
ll mod=1e9+7;

int main(){
  int n;
  cin>>n;
  map<ll,int> m;
  vector<ll> v;
  rep(i,0,n){
    ll a;
    cin>>a;
    if(m[a]==0) m[a]++;
    else{
      v.push_back(a);
      m[a]=0;
    }
  }
  sort(v.rbegin(),v.rend());
  if(v.size()<2){
    cout<<0<<endl;
  }
  else{
    cout<<v[0]*v[1]<<endl;
  }
}