using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Task01.SimulatesExecution
{
    class SimulatesExecution
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            string input = Console.ReadLine();
            char separator = ' ';
            string[] numbers = input.Split(separator);
            decimal[] array = new decimal[n];
            for (int i = 0; i < n; i++)
            {
                array[i] = decimal.Parse(numbers[i]);
            }

            Array.Sort(array);
            decimal result = 0;
            decimal bestResult = 0;
            for (int i = 0; i < 1; i++)
            {
                for (int j = 0; j < 1; j++)
                {
                    for (int k = 0; k < array.Length; k++)
                    {
                        result = (array[n - 1] - array[k])*(array[k] - array[0]);
                        if (result > bestResult)
                        {
                            bestResult = result;
                        }
                    }
                }
            }
            Console.WriteLine(bestResult);
        }
    }
}