# -*- coding:utf-8 -*-

if __name__ == "__main__":
	b = input()
	n = input()
	c = []
	for i in xrange(n):
		c.append(input())
	c.sort()
	mid = n / 2
	flag = 0
	mi = float("INF")
	if mid % 2 == 0:
		flag = 1
	while 1:
		ans, husoku,amari = 0,0,0
		for i in c:
			if i < c[mid]:
				husoku += c[mid] - i
				ans += c[mid] - i
			else:
				ans += i - c[mid]
				amari += i - c[mid]
		if husoku <= (b+amari):
			mi = min(mi,ans)
		if flag == 0 and mi != float("INF"):
			break
		if flag == 1 or mi == float("INF"):
			flag = 0
			mid -= 1
	print mi