import bisect

n,m = map(int,input().split())
a = [-10**9] + list(map(int,input().split())) + [2*10**9+1]
b = [-10**9] + list(map(int,input().split())) + [2*10**9+1]
ans = 0
for i in range(n+1):
    mi,ma = a[i],a[i+1]
    l = bisect.bisect_right(b,mi)
    r = bisect.bisect_left(b,ma) - 1
    print(mi,ma,l,r,ans)
    while l <= r:
        if b[l] - mi < ma - b[r]:
            ans += b[l] - mi
            mi = b[l]
            l += 1
        else:
            ans += ma - b[r]
            ma = b[r]
            r -= 1
print(ans)