#include<bits/stdc++.h>
using namespace std;
int n,m,ans;
int a[100010],b[100010];
int main(){
    ios::sync_with_stdio(0);
    cin>>m>>n;
    for(int i=1;i<=m;i++){
    	cin>>a[i];
	}
	for(int i=1;i<=n;i++){
		cin>>b[i];
	}
	sort(a+1,a+m+1);
	sort(b+1,b+n+1);
	for(int i=1;i<=n;i++){
		int x=lower_bound(a+1,a+m+1,b[i])-a;
		if(b[i]<=a[1]){
			ans+=a[1]-b[i];
		}		
		else{
			ans+=min(abs(a[x]-b[i]),abs(a[x-1]-b[i]));
		}
//		cout<<a[x]<<"\n";
	}
	cout<<ans;
    return 0;
}