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;

#define rep(i,n) for(int i=0;i<(n);i++)
#define fst first
#define snd second
typedef long long ll;

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

  ll ss = 0, ls = 0;

  for(auto x : mp){
    if(x.snd >= 4){
      ss = x.fst;
      ls = x.fst;
    }else if(x.snd >= 2){
      ss = ls;
      ls = x.fst;
    }
  }

  cout << ss * ls << endl;
}