m,n=map(int,input().split())
m_lst=list(map(int,input().split()))
n_lst=list(map(int,input().split()))
m_lst.sort()
n_lst.sort()
w=0
for i in n_lst:
    s=20000000000
    for j in m_lst:
        if abs(i-j)<s:
            s=abs(i-j)
        else:
            break
    w+=s
print(w)