#include <bits/stdc++.h>
using namespace std;
int main()
{
	int m,n;
	cin>>m>>n;
	int school[m+1];
	int student[n+1];
	for(int i=0;i<m;i++)cin>>school[i];
	for(int i=0;i<n;i++)cin>>student[i];
	sort(school,school+m);
	int res=0;
	for(int i=0;i<n;i++)
	{
		int a=abs(student[i]-*lower_bound(school,school+m,student[i]));
		int b=abs(student[i]-*(lower_bound(school,school+m,student[i])-1));
		res+=min(a,b);
	}
	cout<<res;
	return 0;
}