#include<bits/stdc++.h>
using namespace std;
long long mid=0,school[100010],student,n,m;
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>school[i];
	}
	sort(school+1,school+n+1);
	for(int i=1;i<=m;i++){
		cin>>student;
		long long j=lower_bound(school+1,school+n+1,student)-school,a=school[j]-student,b=student-school[j-1];
		if(a>b&&j-1>0){
			mid+=b;
		}
		else{
			mid+=a;
		}
	}
	cout<<mid;
	return 0;
}