def calc(num,c):
	res=0
	for i in c:
		res+=abs(num-i)
	return res

def main():
	b=int(input())
	n=int(input())
	c=list()
	for i in range(n):
		c.append(int(input()))

	c.sort(reverse=True)
	ub=int((sum(c)+b)//n)
	lb=0

	while True:
		left=int((lb*2+ub)/3)
		right=int((lb+ub*2)/3)
		if abs(right-left)<=1:
			break
		if calc(left,c)>calc(right,c):
			lb=left
		else:
			ub=right

	ans=int(1e18)
	for i in range(lb,ub+1):
		ans=min(ans,calc(i,c))
	print(ans)

if __name__=="__main__":
	main()