#include<fstream>
using namespace std;
int n,i,x,x1,x2,x3;

ifstream fin("pba.in");
ofstream fout("pba.out");

int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
    {
        fin>>x;
        if(x>x1)x3=x2,x2=x1,x1=x;
            else
        if(x>x2)x3=x2,x2=x;
            else
        if(x>x3)x3=x;
    }

    fout<<x1*x2*x3;
    return 0;
}