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 <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <math.h>
#include <map>
#include <set>
#include <iomanip>
using namespace std;
typedef long long ll;

int main(){
ll n;cin>>n;
vector<ll> v(n);
for(ll i=0;i<n;i++)cin>>v[i];
sort(v.begin(),v.end());
ll a=0,b=0;
for(ll i=n-1;i>0;i--){
    if(v[i]==v[i-1]&&a==0){a=v[i];i--;}
    else if(a!=0&&v[i]==v[i-1]){b=v[i];break;}
}
cout<<a*b;
}