#include<bits/stdc++.h>
using namespace std;
const int N=100010;
int n,m;
int a[N],b[N];

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+1+n);  //学校
    int sum=0;
	for(int i=1;i<=m;++i)
	{
		int ans=1e9;
		int l=0,r=n+1;
		while(l+1<r)
		{
			int mid=(l+r)/2;
			if(a[mid]<b[i])
			{
				l=mid;
				ans=min(ans,abs(b[i]-a[l]));
			}
			else if(a[mid]>b[i])
			{
				r=mid;
				ans=min(ans,abs(b[i]-a[r]));
			}
			else
			{
				ans=0;
				break;
			}
		}
		sum+=ans;
	}
	cout<<sum<<'\n';
	return 0;	
}