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;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main(){
  ll N;cin>>N;
  vector<ll> A(N);rep(i,N)cin>>A[i];
  sort(A.begin(),A.end(),greater<ll>());
  ll i=0,k=0,edge[2];
  edge[0]=0;edge[1]=0;
  while(k<2&&i<N-1){
    if(A[i]==A[i+1]){
      edge[k]=A[i];
      ++k;
      ++i;
    }
    ++i;
  }
  cout << edge[0]*edge[1] << endl;
}