#include<bits/stdc++.h>
using namespace std;
const int N=1e6+10;
int m,n,a[N],b[N];
long long sum=0;

int bmy(int k){
	int l=0,r=m-1;
	while(l<r){
		int mid = (l+r+1)/2;
		if(a[mid]>k) r=mid-1;
		else if(a[mid]==k) return 0;
		else l=mid;
//		cout<<"1 "<<l<<" "<<r<<endl;
	}
	int ll=l;
	l=0,r=m-1;
	while(l<r){
		int mid = (l+r)/2;
		if(a[mid]>k) r=mid;
		else if(a[mid]==k) return 0;
		else l=mid+1;
//		cout<<"2 "<<l<<" "<<r<<endl;
	}
	int rr=l;
//	cout<<k<<" "<<a[ll]<<" "<<a[rr]<<endl;
	return min(abs(k-a[ll]),abs(a[rr]-k));
}

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