#include<iostream>
#include<algorithm>
using namespace std;
int n1[100005];
int m1[100005];
int main(){
	int n=0,m=0,sum=0;//n时人数，m时学校 
	cin>>m>>n;
	for(int i=1;i<=n;i++)cin>>n1[i];
	for(int i=1;i<=m;i++)cin>>m1[i];
	sort(m1+1,m1+1+m);
	for(int i=1;i<=n;i++){
	int l=0,r=m-1;
	int tot=1e9;
	while(l<=r){
		int mid=l+(r-l)/2;;
		if(m1[mid]==n1[i]){
			tot=0;
			break;
		}
		else if(m1[mid]<n1[i]){
			tot=min(tot,abs(m1[mid]-n1[i]));
			l=mid+1;
		}
		else if(m1[mid]>n1[i]){
			tot=min(tot,abs(m1[mid]-n1[i]));
			r=mid-1;
		}
		}
		sum+=tot;
	}
	cout<<sum;
}