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package sutaz;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Scanner;

/**
 *
 * @author janotka1
 */
public class Marathon {
   public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextInt()) {
            int stands = sc.nextInt();
            int distance = sc.nextInt();
            int sum = 0;
            HashMap<Integer, Integer> currentPositions = new HashMap<>();
            for(int i =0; i < stands; i++) {
                int pos = sc.nextInt();
                sum += pos;
                currentPositions.put(pos, pos);
            }
            int avg = sum / stands;
            sumOfChange(currentPositions, avg, distance);
        }
        
        
   }
   
   public static void sumOfChange(HashMap<Integer, Integer> currentPositions, int avg, int distance) {
       int median = 0;
       int indexOfMedian = 0;
       int[] arrayOfsort = new int[currentPositions.size()];
       
       int i = 0;
       for(Integer intik : currentPositions.keySet()) {
           if(Math.abs(median - avg) > Math.abs(intik - avg)) {
               median = intik;
               indexOfMedian = i;
           }
           arrayOfsort[i] = intik;
           i++;
       }
       
       int minSum = Integer.MAX_VALUE;
               
       for(i = 0; i < arrayOfsort.length; i++) {
           int sum = 0;
            int countBG = 0;
            int countSM = 0;
           for(int j = 0; j < arrayOfsort.length; j++) {
               if(arrayOfsort[i] < arrayOfsort[j] && i != j) {
                   countSM++;
                   sum += arrayOfsort[j] - (countSM * distance + arrayOfsort[i]);
               }
               if(arrayOfsort[i] > arrayOfsort[j] && i != j) {
                   countBG++;
                   sum += (arrayOfsort[i] - countBG * distance) - arrayOfsort[j];
               }
            }
           
           if(minSum > sum) {
               minSum = sum;
           }
          
       }
       
      
       System.out.println(minSum);
     
   }
   
   
}