#include<bits/stdc++.h>
#define str to_string
using namespace std;
using ll=long long;
const int MAX=1e5+1;
int n,m,a[MAX],b[MAX];
bool check(int mid,int tar){
	return a[mid]<tar;
}
int Reason(int tar){
	int l=1,r=n;
	while(l<=r){
		int mid=(l+r)>>1;
		if(check(mid,tar))l=mid+1;
		else r=mid-1;
	}
	return min(abs(a[l-1]-tar),abs(a[l]-tar));
}
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1;i<=m;i++)cin>>b[i];
	sort(a+1,a+n+1);
	int ans=0;
	for(int i=1;i<=m;i++)ans+=Reason(b[i]);
	cout<<ans<<'\n';
	return 0;
}