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;
typedef unsigned long long ull;
int main(){
    
    int N; cin >> N;
    int data[N],ans[2] ={0,0};
    for(int i=0;i<N;i++) cin >> data[i];
    sort(data,data+N,greater<int>());
    int index=0;
    for(int i=0;i<N-1;i++){
        if(data[i] == data[i+1]){ans[index] = data[i]; index++; i++;}
        if(index == 2) break;
    }
    cout << (ull)ans[0] * ans[1] << endl;
}