import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.util.stream.IntStream;

/**
 * Created by nullzine on 2017/01/12.
 */
public class Main {

    public static void main(String[] args){
        new Main().run();
    }

    private void run(){
        Scanner sc = new Scanner(System.in);
        int[] data = new int[Integer.parseInt(sc.nextLine())];
        int k = Integer.parseInt(sc.nextLine());
        for(int i=0;i<data.length;i++){
            data[i]=Integer.parseInt(sc.nextLine());
        }
        System.out.println((int)new PermutationExecution(data,k).getResult());
    }

}

class PermutationExecution{

    private int[] data;
    private int k;
    private double result;

    public PermutationExecution(int[] data,int k){
        this.data=data;
        this.k=k;
        result=roundUp(calculation());
    }

    private double roundUp(double num){
        return num;
        /*
        if(0.0<(1.1%1)){
            return (int)(num+1);
        }else{
            return (int)num;
        }
        */
    }

    private double calculation(){
        String[] permutations = permutation(k,data.length);
        Result[] avgResult = new Result[permutations.length];
        IntStream.range(0,avgResult.length).parallel().forEach(e->avgResult[e]=calcAvgsub(permutations[e]));
        double ret = Double.MIN_VALUE;
        for(Result result:avgResult){
            //System.out.println(result);
            if(ret<result.maxAvarage-result.minAvarage){
                ret=result.maxAvarage-result.minAvarage;
            }
        }
        return ret;
    }

    private Result calcAvgsub(String pattern){
        NumberGroup[] numberGroups = new NumberGroup[k];
        for(int i=0;i<numberGroups.length;i++){
            numberGroups[i] = new NumberGroup();
        }
        for(int i=0;i<pattern.length();i++){
            numberGroups[Integer.parseInt(pattern.charAt(i)+"")].add(data[i]);
        }
        double maxAvg = Double.MIN_VALUE;
        double minAvg = Double.MAX_VALUE;
        for(NumberGroup ng:numberGroups){
            if(ng.isEmpty()){
                return new Result(0,0,"none",numberGroups);
            }
            if(maxAvg<ng.getAvarage()){
                maxAvg=ng.getAvarage();
            }
            if(ng.getAvarage()<minAvg){
                minAvg=ng.getAvarage();
            }
        }
        return new Result(maxAvg,minAvg,pattern,numberGroups);
    }

    private String[] permutation(int a,int b){
        String[] ret = new String[(int)Math.pow(a,b)/2];
        IntStream.range(0,ret.length).parallel().forEach(e->ret[e]=genPattern(a,b,e));
        return ret;
    }

    private String genPattern(int a,int b,int c){
        String ret = "";
        while(c!=0){
            ret=(c%a)+ret;
            c/=a;
        }
        return complementStr(ret,b);
    }

    private String complementStr(String str,int limit){
        for(int i=str.length();i<limit;i++){
            str="0"+str;
        }
        return str;
    }

    public double getResult(){
        return result;
    }

}

class Result{

    public double maxAvarage;
    public double minAvarage;
    private String pattern;
    private NumberGroup[] ngs;

    public Result(double maxAvarage,double minAvarage,String pattern,NumberGroup[] ngs){
        this.maxAvarage=maxAvarage;
        this.minAvarage=minAvarage;
        this.pattern=pattern;
        this.ngs=ngs;
    }

    public String toString(){
        StringBuilder sb = new StringBuilder();
        for(NumberGroup ng:ngs){
            sb.append(ng);
        }
        return pattern+" "+maxAvarage+" "+minAvarage+" "+sb.toString();
    }

}

class NumberGroup{

    private ArrayList<Integer> list;

    public NumberGroup(){
        list = new ArrayList<>();
    }

    public void add(int n){
        list.add(n);
    }

    public boolean isEmpty(){
        return list.isEmpty();
    }

    public double getAvarage(){
        double ret = 0.0;
        for(int n:list){
            ret+=n;
        }
        return ret/list.size();
    }

    public String toString(){
        StringBuilder sb = new StringBuilder();
        sb.append("{");
        for (int n:list){
            sb.append(n+",");
        }
        sb.append("}");
        return sb.toString();
    }

}