#include<bits/stdc++.h>
using namespace std;
int n,m,a[10000001],b[10000001];
int ef(int x,int l,int r){
    while(l<=r){
        int mid=l+(r-l)/2;
        if(b[mid]==x)return 0;
        if(b[mid]<x)l=mid+1;
        else r=mid-1;}
        if(r<1)return abs(b[1]-x);
        if(l>n)return abs(b[n]-x);
        return min(abs(b[l]-x),abs(b[r]-x));
    
}
    int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin>>n>>m;
for(int i=1;i<=n;i++)cin>>b[i];
for(int i=1;i<=m;i++)cin>>a[i];
sort(b+1,b+n+1);
long long ans=0;
for(int i=1;i<=m;i++)ans+=ef(a[i],1,n);
cout<<ans;
return 0;}
/**************************************************************
	Problem: 1899
	User: zhengzihao
	Language: C++
	Result: Accepted
	Time:169 ms
	Memory:80360 kb
****************************************************************/