#include<bits/stdc++.h>
using namespace std;
long long n,m,a[1000006],b[1000006],ans;
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+n+1);
   for(int i=1;i<=m;i++){
   	long long l=1,r=n;
   	while(l<=r){
   	long long m=(l+r)/2;
   	if(b[i]>=a[m])l=m+1;
   	if(b[i]<a[m])r=m-1;
   }
   if(b[i]<=a[1])ans+=a[1]-b[i];
   else ans+=min(abs(a[l-1]-b[i]),abs(a[l]-b[i]));
   }
   cout<<ans;
   return 0;
}

/**************************************************************
	Problem: 1899
	User: chenjingqi
	Language: C++
	Result: Accepted
	Time:139 ms
	Memory:17704 kb
****************************************************************/