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 x = 0, y = 0;
    int N;
    cin >> N;
    map<ll, int>cnt;
    for(int i = 0; i < N; i++){
        ll a;
        cin >> a;
        cnt[a]++;
        if(x < y)swap(x, y);
        if(cnt[a]>=2 && y < a){
            cnt[a] -= 2;
            y = a;
        }
    }
    cout << x * y << endl;

    return 0;
}