# include <bits/stdc++.h>

using namespace std;

int main()
{
	int n,m;
	cin >> m >> n;
	int a[n],b[m];
	for(int i = 0;i < m;i ++)
	{
		cin >> a[i];
	}
	for(int i = 0;i < n;i ++)
	{
		cin >> b[i];
	}
	sort(a,a + m);
	long long sum = 0;
	for(int i = 0;i < n;i ++)
	{
		int x = lower_bound(a,a + m,b[i]) - a;
		sum += min(abs(a[x] - b[i]),abs(a[x == 0 ? 0 : x - 1] - b[i]));
	}
	cout << sum;
	return 0;
}