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<map>
using namespace std;
using ll=long long;
map<ll,int> mp;
int main(){
    int N;cin>>N;
    for(int i{};i<N;++i){
        ll A;cin>>A;
        ++mp[A];
    }
    ll a[2]={},i{};
    for(auto p{mp.rbegin()};p!=mp.rend();++p)
        if(p->second>=2){
            a[i]=p->first;++i;
            if(i>1)break;
            if(p->second>=4){a[i]=p->first;break;}
        }
    cout<<a[0]*a[1]<<endl;
}
