#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
using namespace std;
#define _int long
_int n,m,a[1000001],b;
_int rfen(_int x)
{
	_int l=1,r=n;
	while(l<r)
	{
		_int mid=(r+l)/2;
		if(a[mid]>=x)r=mid;
		else l=mid+1;
	}
	return l;
}
int main(){
	  _int ans=0;
     scanf("%d%d",&n,&m); 
     for(_int i=1;i<=n;i++)
      scanf("%d",&a[i]);
      sort(a+1,a+n+1);
      for(_int i=1;i<=m;i++)
       {
       	scanf("%d",&b);
       	_int c=rfen(b);
       	if(c==1)ans+=a[c]-b;
        else if(a[c]==b)ans+=0;
       	else if(a[c]-b<b-a[c-1])ans+=a[c]-b;
       	else ans+=fabs(a[c-1]-b);
	  }
	  cout<<ans;
}