#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int cmp(const void*a,const void*b){
	return (*(int*)a-*(int *)b);
}

int main()
{
	int n,m;
	scanf("%d %d",&n,&m);
	int a[n+5],b[m+5],i;
	for(i=0;i<n;i++){
		scanf("%d",&a[i]);
	}
	qsort(a,n,sizeof(int),cmp);
	for(i=0;i<m;i++){
		scanf("%d",&b[i]);
	}
	//qsort(b,m,sizeof(int),cmp);	
	
	long long s=0;
	int flag=0;
	for(i=0;i<m;i++){
	int left=0,right=n-1;
	while(left<=right){
		int mid=(right-left)/2+left;
		if(b[i]<a[mid]) right=mid-1;
		else if(b[i]>a[mid])left=mid+1;
		else if(b[i]==a[mid]){
		 break;flag=1;}
	}
	if(flag==1){
		s=s+0;
	}
	if(flag==0){
	int x2=abs(a[left]-b[i]),min;
	if(left!=0&&left!=n-1){
	int x1=abs(a[left-1]-b[i]);
	int j;
		min=x1;
		for(j=left-1;j<=left+1;j++) 
			if(abs(a[j]-b[i])<min) min=abs(a[j]-b[i]);
		
	}
    else if(left==0){
	int x3=abs(a[left+1]-b[i]);
	min=x2<=x3?x2:x3;
	}
	else if(left==n-1){
		
		int x1=abs(a[left-1]-b[i]);
		min=x2<=x1?x2:x1;
		
	}
		s=s+min;
	}
	
}
	printf("%lld",s);
}