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(){
    int N;
    cin>>N;
    vector<ll>a;
    for(int i=0;i<N;i++){
        ll t;
        cin>>t;
        a.push_back(t);
    }
    sort(a.begin(), a.end());
    ll max1=0,max2=0;
    for(int i=1;i<N;i++){
        if(a[i-1]==a[i]){
            max2=max1;
            max1=a[i];
            i++;
        }
    }
    cout<<max1*max2<<endl;
    return 0;
}
