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++)

int main(){
  int n;cin>>n;
  long long sh=0,lo=0;
  map<long long, int> mp;
  REP(i,n){
    long long t;cin>>t;
    mp[t]++;
  }
  for(auto p:mp){
    if(p.second>=2&&p.second<4){
      sh=lo;
      lo=p.first;
    }else if(p.second>=4){
      sh=lo=p.first;
    }
  }
  
  cout<<sh*lo;
}