#include<bits/stdc++.h>
using namespace std;
int m,n,a[100005],b,minn,sum;
bool cmp(int x,int y){
	return x>y;
}
int main(){
	cin>>m>>n;
	for(int i=1;i<=m;i++) cin>>a[i];
	sort(a+1,a+1+n,cmp);
	for(int i=1;i<=n;i++){
		cin>>b;
		minn=INT_MAX;
		int l=1,r=m;
		while(l<r){
			int mid=(l+r)/2;
			if(a[mid]<b) r=mid;
			else l=mid+1;
		}
		sum+=min(abs(a[l]-b),abs(a[l+1]-b));
	}
	cout<<sum<<endl;
	return 0;
}