#include<bits/stdc++.h>
using namespace std;
int sc[100005],m,n;
int stu,maxx,ans;
int main(){
	scanf("%d%d",&m,&n);
	for(int i=1;i<=m;i++)
		scanf("%d",&sc[i]);
	sort(sc+1,sc+m+1);
	for(int i=1;i<=n;i++){
		scanf("%d",&stu);
		ans+=min(abs(sc[lower_bound(sc+1,sc+m,stu)-sc]-stu),abs(stu-sc[(lower_bound(sc+1,sc+m,stu)-sc)-1]));
	}
	printf("%d",ans);
	return 0;

}