import java.util.*;

public class Run {
    public static void main (String arg[]) {
        Scanner scan = new Scanner(System.in);
        int N = scan.nextInt();
        int K = scan.nextInt();
        if (N < 3||N > 9||K < 3||K > N) System.exit(1);
        int[] n = new int[N];
        int max = 0, min = 1001;
        for (int i = 0; i < N; i++) {
            n[i] = scan.nextInt();
            if (n[i] < 1||n[i] > 1000) System.exit(1);
            if (max < n[i]) max = n[i];
            if (min > n[i]) min = n[i];
        }

        System.out.println(max - min);
    }
}