#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include<iostream>
#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
int main()
{
	int m, n,ans=0;
	cin >> m >> n;
	priority_queue<int>uni;
	priority_queue<int>stu;
	int minx = 2147483647;
	int aa, bb;
	for (int i = 1; i <= m; i++)
	{
		cin >> aa;
		uni.push(aa);
	}
	for (int i = 1; i <= n; i++)
	{
		cin >> bb;
		stu.push(bb);
	}
	while (!stu.empty())
	{
		
		minx = min(minx, abs(uni.top() - stu.top()));
		int cc = uni.top();
		if (uni.size() > 1) 
		{
			uni.pop();
			if (abs(uni.top() - stu.top()) > minx)
			{
				stu.pop();
				ans += minx;
				minx = 2147483647;
				uni.push(cc);
			}
		}
		else 
		{
			
			ans += abs(uni.top() - stu.top());
			stu.pop();
		}
	}
	cout << ans << endl;
	return 0;
}