import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

N,M,*D = map(int,read().split())

L = [-x for x in D if x < 0]
R = [x for x in D if x >= 0]

L.sort()
R.sort()

INF = 10 ** 18
L = [0] + L + [INF] * N
R = [0] + R + [INF] * N

cand = [L[N], R[N]]
for n in range(1, N):
    cand.append(L[n] * 2 + R[N-n])
    cand.append(R[n] * 2 + L[N-n])

answer = min(cand)
print(answer)