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;

int main(){
  
    long long int N,no1=0,no2=0;
    cin>>N;
    map<long long int,int> A;
    for(int i=0;i<N;i++){
        long long int k;cin>>k;
        A[k]++;
        if(A[k]==2){
            if(k>=no1){
                no2=no1;
                no1=k;
            }
            else if(k>no2) no2=k;
            A[k]-=2;
        }
    }
    cout<<no1*no2<<endl;
}
