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;
const int N = 1000010;
int n, mx;
int a[N];

int main() {
	scanf("%d", &n);
	for(int i = 1; i <= n; ++i) scanf("%d", &a[i]);
	sort(a + 1, a + n + 1);
	ll ans = 1ll, cnt = 0;
	for(int i = n; i; i--) {
		if(a[i] == a[i - 1]) ans *= a[i], ++cnt, --i;
		if(cnt == 2) break; 
	}
	if(cnt == 2) printf("%lld\n", ans);
	else printf("0");
}
