#include<bits/stdc++.h>
using namespace std;
int a[100005],b[100005],l,r,tot=0,n,m;

int binary(int x)
{
	l=0,r=n-1;
	while(l<=r)
	{
		int mid=(l+r)/2;
		if(x<a[mid]&&x>a[mid-1]) return min(abs(a[mid-1]-x),abs(a[mid]-x));
		else if(x>a[mid]&&x>a[mid-1]) l=mid+1;
		else if(x<a[mid]&&x<a[mid+1]) r=mid-1;
	}
}

int main()
{
	cin>>n>>m;
	for(int i=0;i<n;i++) cin>>a[i];
	for(int i=0;i<m;i++) cin>>b[i];
	sort(a,a+n);
	for(int i=0;i<m;i++) tot+=binary(b[i]);
	cout<<tot;
	return 0;
}