#include <bits/stdc++.h>
using namespace std;

long long a[100010];
long long b[100010];

int main()
{
    long long m,n,cnt = 0;
    cin >> m >> n;
    a[0] = 1145141919810;
    a[m] = 1145141919810;
    for(long long i = 1;i <= m;i++)
        cin >> a[i];
    sort(a + 1,a + m + 1);
    for(long long i = 1;i <= n;i++)
    {
        cin >> b[i];
        long long l = lower_bound(a + 1,a + m + 1,b[i]) - a;
        cnt += min(a[l] - b[i],b[i] - a[l - 1]);
    }
    cout << cnt;
    return 0;
}