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;
using ll = long long;

int main() {
    int N; cin >> N;
    map<int, int> m;
    ll ans1=0, ans2=0;
    for (int i = 0; i < N; i++){
        ll a; cin >> a;
        m[a]++;
        if(m[a]==2){
            m[a] = 0;
            if(a>ans1) swap(a,ans1);
            if(ans1>ans2) swap(ans1, ans2);
        }
    }

    cout << ans1 * ans2 << endl;
}