gaokao

/*
 Author: 曹北健
 Result: AC Submission_id: 4348277
 Created at: Tue Apr 19 2022 20:16:40 GMT+0800 (China Standard Time)
 Problem_id: 3339   Time: 381   Memory: 2320
*/

#include <stdio.h>
#include <stdlib.h>
#define MAX(a,b) (((a)>(b))?(a):(b))
#define MIN(a,b) (((a)<(b))?(a):(b))
int compare(const void *p,const void *q){
    int a = *(int *)p,b = *(int *)q;
    if(a < b)return -1;
    else if(a > b)return 1;
    else return 0;
}
void *lowerbound(void *key,void *base,size_t count,size_t itemsize,int(*compare)(const void *,const void *)){
    size_t lo = 0,hi = count - 1,mid = 0;
    if(compare(key,(char *)base + hi * itemsize) > 0){
        return (char *)base + count * itemsize;
    }
    char *pmid = 0;
    while(lo < hi){
        mid = (lo + hi) >> 1;
        pmid = ((char *)base) + mid * itemsize;
        if(compare(pmid,key) < 0){
            lo = mid + 1;
        }
        else{
            hi = mid;
        }
    }
    return (char *)base + lo * itemsize;
}
int a[1919810] = {0};
int main(){
    int i,n,m,t;
    long long ans = 0;
    scanf("%d%d",&m,&n);
    for(i = 1;i <= m;i++){
        scanf("%d",a + i);
    }
    qsort(a + 1,m,sizeof(int),compare);
    while(n--){
        scanf("%d",&t);
        int *lb = (int *)lowerbound(&t,a + 1,m,sizeof(int),compare);
        int pos = lb - a;
        if(pos > 1){
            ans += MIN(abs(a[pos] - t),abs(a[pos - 1] - t));
        }
        else{
            ans += abs(a[pos] - t);
        }
    }
    printf("%lld\n",ans);
    return 0;
}