#include<bits/stdc++.h>
using namespace std;
int a[100100]={0};
int b[100100]={0};
int m,n,i;

int zuoerfen(int x) //左二分查找
{
	int left=-1,right=m,mid;
	while (left+1<right)
	{
		mid=(left+right)/2;
		if (x<=a[mid])
		{
			right=mid;
		}
		else
		{
			left=mid;
		}
	}
	return right;
} 

int youerfen(int x) //右二分查找
{
	int left=-1,right=m,mid;

	while (left+1<right)
	{
		mid=(left+right)/2;
		if (x<a[mid])
		{
			right=mid;
		}
		else
		{
			left=mid;
		}

	}
	return left;
}

int main()
{
	scanf("%d %d",&m,&n);
	for (i=0;i<m;i++)
	{
		cin>>a[i];
	}
	for (i=0;i<n;i++)
	{
		cin>>b[i];
	}
	sort(a,a+m);
	long long sum=0; 
	for (i=0;i<n;i++)
	{
		int ansL=zuoerfen(b[i]);
		int ansR=youerfen(b[i]);
		if (ansL<0)
		{
			ansL=0;
		}
		if (ansL>=m)
		{
			ansL=m-1;
		}
		if (ansR<0)
		{
			ansR=0;
		}
		if (ansR>=m)
		{
			ansR=m-1;
		}//比较大小
		sum+=min(abs(b[i]-a[ansL]),abs(b[i]-a[ansR]));
	}
	cout<<sum<<endl;
	return 0;
}