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<queue>
using namespace std;
int main(){
long long n, a,t1[2]={},cnt=0,ans=0;
priority_queue<long long> q;
cin>>n;
for(int i=0;i<n;i++){
cin>>a;
q.push(a);
}
while(q.size()-1){
long long tmp=q.top();
q.pop();
if(tmp==q.top()){
q.pop();
t1[cnt]=tmp;
cnt++;
}
if(cnt==2)break;
}
if(cnt==2)cout<<t1[0]*t1[1];
else cout<<'0';
return 0;
}