#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;
typedef long long ll;
ll ans = 0;
ll m, n;
ll a[1000010];
ll test(ll x)
{
	ll left = 0;
	ll right = m + 1;
	while (left < right)
	{
		ll mid = left + (right - left) / 2;
		if (a[mid] == x)
		{
			return 0;
		}
		if (a[mid] > x)
		{
			right = mid;
		}
		else if(a[mid]<=x)
		{
			left = mid + 1;
		}

	}
	if (x <= a[1])
	{
		ans = a[1] - x;
	}
	else
	{
		ans = min(abs(a[left - 1] - x), abs(a[left] - x));
	}
	return ans;
}
int main()
{
	ll c;
	ll anp = 0;
	scanf("%lld %lld", &m, &n);
	for (ll i = 1; i <= m; i++)
	{
		scanf("%lld", &a[i]);
	}
	sort(a+1, a + m+1);
	for (ll i = 1; i <= n; i++)
	{
		scanf("%lld", &c);
		anp = anp + test(c);
	}
	printf("%lld", anp);

	return 0;
}