#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;

const int N=100010;

int m,n;
int school[N],stu[N];


int main()
{
    scanf("%d %d",&m,&n);
    for(int i=1;i<=m;i++)
        scanf("%d",&school[i]);
    for(int i=1;i<=n;i++)
        scanf("%d",&stu[i]);
    sort(school+1,school+1+n);
    long long sum=0;
    for(int j=1;j<=n;j++)
    {
        int l=0,r=m;
        int ans=1e9;
        while(l+1<r)
        {
            int mid=(l+r)/2;
            if(school[mid]==stu[j])
            {
                ans=0;
                break;
            }
            else if(school[mid]<stu[j])
            {
                ans=min(ans,abs(school[mid]-stu[j]));
                l=mid;
            }
            else
            {
                ans=min(ans,abs(school[mid]-stu[j]));
                r=mid;
            }
        }
        sum+=ans;
    }
    printf("%lld\n",sum);
    return 0;
}