#include<bits/stdc++.h>
using namespace std;
int m,n,h=0,a[100005],b[100005],x;
void f(int l,int r){
	int mid=(l+r)/2;
	if(abs(a[mid]-x)<abs(a[mid-1]-x)&&abs(a[mid]-x)<abs(a[mid+1]-x)) h+=abs(a[mid]-x);
	else if(abs(a[mid]-x)<abs(a[mid+1]-x)) f(l,mid-1);
	else f(mid+1,r);
} 
int main() {
  	cin>>m>>n;
    for(int i=1;i<=m;i++){
    	scanf("%d",&a[i]);
	}
	for(int i=1;i<=n;i++){
		scanf("%d",&b[i]);
	}
	for(int i=1;i<=n;i++){
		sort(1+a,1+a+m);
		x=b[i];
		f(1,m);
	} 
	cout<<h;
    return 0;
}
/**************************************************************
	Problem: 1899
	User: panyuchen
	Language: C++
	Result: Time Limit Exceed
****************************************************************/