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;

int main(){
    ll N; cin>>N;
    vector<ll>a(N);
    for(int i=0;i<N;i++)scanf("%lld",&a[i]);

    sort(a.begin(),a.end(),greater<ll>());
    ll h=0,w=0;
    for(int i=0;i<N;i++){
        if(h!=0&&w!=0)break;
        if(a[i]==a[i+1]){
            if(h==0)h=a[i];
            else w=a[i];
            i++;
        }
    }
    cout << h*w << endl;
}
