#include <bits/stdc++.h>
using namespace std;
int m,n,a[100005],b[100005];
long long ans;
int main()
{
	cin >> m >> n;
	for (int i = 1;i <= m;i++)
	{
		cin >> a[i];
	}
	for (int i = 1;i <= n;i++)
	{
		cin >> b[i];
	}
	sort(a + 1,a + m + 1);
	sort(b + 1,b + n + 1);
	for (int i = 1;i <= n;i++)
	{
		int p = lower_bound(a + 1,a + n + 1,b[i]) - a;
		if (b[p] == a[i])
		{
			continue;
		}
		else
		{
			ans += min(abs(b[i] - a[p]),abs(b[i] - a[p - 1]));
		}
	}
	cout << ans;
	return 0;
}