#!/usr/bin/env python3
#fileencoding: utf-8

from math import ceil

N = int(input())
K = int(input())
n = sorted([int(input()) for i in range(N)])

max_avg = n[-1]
max_group_size = N - ceil(N/K)

min_avg = n[0]
for i in range(1,max_group_size):
    tmp = ceil(sum(n[:i+1]) / (i+1))
    if min_avg >= tmp:
        min_avg = tmp
    else:
        break
print(max_avg - min_avg)