#include <iostream>
#include <algorithm>

using namespace std;
const int N = 1e6 + 10;
int a[N], b[N];
int n, m, ans=0;
int find(int x)
{
    int l = 1, r = n;
    while (l < r)
    {
        int mid = r + l >> 1;
        if (a[mid] == x)
        {
            return mid;
        }
        if (a[mid] >= x)
            r = mid;
        else
            l = mid+1;
    }
    return l;
}

int main()
{

    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    sort(a + 1, a + 1 + n);
    for (int i = 1; i <= m; i++)
    {
        cin >> b[i];
        if (b[i] > a[n]) ans += b[i] - a[n];
        else if (b[i] < a[1]) ans += a[1] - b[i];
        else
        {
            int e = find(b[i]);
               ans += min(abs(a[e] - b[i]), abs(b[i] - a[e - 1]));
        }
    }
    cout << ans;
    return 0;
}