m,n,*a = map(int,open(0).read().split())
from bisect import bisect_left
a.sort()
v = bisect_left(a,0)
ans = 10**9
for i in range(min(m,v)+1):
    j = v + m-i - 1
    if j >= n: continue
    x = (-2*a[v-i] if i else 0) + (a[j] if m-i else 0)
    ans = min(x,ans)
    x = (-a[v-i] if i else 0) + (2*a[j] if m-i else 0)
    ans = min(x,ans)
print(ans)