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;

const int N = 100010;

int a[N], n, len;
map<int, int> cnt;

long long l, r;

int main() {
	scanf("%d", &n);
	for(int i = 0; i < n; ++i) {
		scanf("%d", &len);
		cnt[len]++;
	}



	for(auto v : cnt) {
		if(v.second >= 2) {
			if(l < v.first)
				l = v.first;
		}
	}

	cnt[l] -= 2;

	for(auto v : cnt) {
		if(v.second >= 2) {
			if(r < v.first)
				r = v.first;
		}
	}

	cout << l * r << "\n";
}