using System;

public class Program

{

    //https://www.hackerearth.com/practice/algorithms/sorting/bubble-sort/practice-problems/algorithm/min-max-difference/description/

​

    public static void Main()

    {

        int[] arr = {1, 5, 2, 8, 4, 6, 1};

​

        //first sort the array, then we can get sum of first 4 (n - m) and sum of last 4 elements which are the min and max values

        //of the array.

​

        arr = BubbleSort(arr);

​

        CalculateDifference(arr);

    }

​

    //sort the array

    public static int[] BubbleSort(int[] arr){

        int temp = 0;

        bool swap = false;

​

        //As the array is very random, we can use Merge sort whose time complexity is O(nlogn) in best, average and worst case.

        //Here I am using bubble sort, just for practising bubble sort algorithm

        //Since bubble sort is used, time complexity will be O(n square) in worst case, and if no swapping done, which means 

        //array is already sorted and time complexity will be O(n) which is the best case.

        for (int i = 0; i < arr.Length; i++){

            for (int j = 0; j < arr.Length - i - 1; j++)

            {

                if (arr[j] > arr[j+1]){

                    //swap

                    swap = true;

                    temp = arr[j];

                    arr[j] = arr[j+1];

                    arr[j+1] = temp;

                }

            }

            if (!swap)

            {

                break;

            }

        }

        return arr;

    }

​

    public static void CalculateDifference(int[] arr){

        int n = 7;

        int m = 3;

        int subArrSize = n - m;

        int minSum = 0;

        int maxSum = 0;

​

        //now from the sorted array, get the sum of first 4 elements (min) and last 4 elements (max)

        for (int i = 0; i < arr.Length; i++){

            //min sum

            if (i < subArrSize)

            {

                minSum = minSum + arr[i];

            }

​

            //max sum

            if (i >= arr.Length - subArrSize){

                maxSum = maxSum + arr[i];

            }

        }

​

        //print the sum

        Console.WriteLine(maxSum - minSum);

    }

}