#include<iostream>
#include<algorithm>
using namespace std;
typedef long long ll;
int mian;
int n,a[114514]={0},b[114514]={0},l,r;
ll ans=0;
int er(int k){
	l=1;
	r=mian;
	while(l<r){
		int m=(l+r+1)/2;
		if(a[m]<k) l=m;
		else r=m-1;
	}
	return l;
}
const int maxx=0x3f3f3f,minn=-0x3f3f3f;
int main(){
//	freopen("doc.in","r",stdin);
//	freopen("doc.out","w",stdout);
	cin>>mian>>n;
	for(int i=1;i<=mian;i++){
		cin>>a[i];
	}
	for(int i=1;i<=n;i++){
		cin>>b[i];
	}
	sort(a+1,a+mian+1);
	for(int i=1;i<=n;i++){
		int t=er(b[i]);
			ans+=min(abs(a[t]-b[i]),abs(a[t+1]-b[i]));
	}
	printf("%lld",ans);
    return 0;
}