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;
long long n,a,mx1=0,mx2=0;
map<long long,long long> mp;
int main(){
	scanf("%lld",&n);
	for(int i=1;i<=n;i++){
		scanf("%lld",&a);
		if(mp[a] == 0){
			mp[a] = 1;
		}
		else{
			mp[a] = 0;
			if(a > mx1){
				mx2 = mx1;
				mx1 = a;
			}
			else if(a > mx2){
				mx2 = a;
			}
		}
	}
	printf("%lld",mx1*mx2);
}