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,a,p;
    cin>>n;
    map<int,int>mp;
    vector<int>v;
    for(int i=1;i<=n;i++)
    {
        cin>>a;
        mp[a]++;
        if(mp[a]==2){v.push_back(a);mp[a]=0;}
    }
    sort(v.begin(),v.end());
    p=(int)v.size();
    if(p<2) cout<<"0"<<endl;
    else cout <<((long long int)v[p-1]*v[p-2])<<endl;
    return 0;
}
