#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int MAXM = 1e5 + 10;
ll fs[MAXM] , ls[MAXM];
int main(){
	//freopen("P1678_1.in","r",stdin);
	//freopen("P1.out","w",stdout);
	ll n,m;
	ll ans = 0;
	cin >> n >> m;
	for(int i = 1; i <= n;i++){
		scanf("%d",&fs[i]);
	}
	for(int i = 1;i <= m;i++){
		scanf("%d",&ls[i]);
	}
	sort(fs + 1,fs + n + 1);
	sort(ls + 1,ls + m + 1);
	for(int i = 1;i <= m;i++){
		if(ls[i] > fs[n]){
			ans += ls[i] - fs[n];
		}
		else{
			ans += min(abs(fs[lower_bound(fs + 1,fs + n + 1,ls[i]) - fs ] - ls[i]), abs(fs[lower_bound(fs + 1,fs + n + 1,ls[i]) - fs - 1] - ls[i]));
		}
	}
	cout << ans ;
	return 0;
}