找到位置，别忘记做差的绝对值，前后比较得出最小的期望值。
//#include<bits/stdc++.h>
#include <stdio.h>
#include <iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<vector>
#include<queue>
#define ll long long
#define ios ios::sync_with_stdio(false);cin.tie(0)
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define fep(i,a,b) for(int i=b;i>=a;--i)
#define scf(x) scanf("%lld",&x)
#define prf(x) printf("%lld\n",x)
#define deprf(x) printf("[%lld]\n",x)
#define mem(x,y) memset(x,y,sizeof(x))
#define inf 2147483647
const int mod=1e9+7;
const int maxn=1e5+7;
using namespace std;
int maxnn = 1e8;
int read(){//快读
int x=0,f=1;
char c=getchar();
while(c<'0'||c>'9'){
if(c=='-') f=-1;
c=getchar();
}
while(c>='0'&&c<='9'){
x=x*10+c-'0';
c=getchar();
}
return x*f;
}
void sovle()
{
}
int a[maxn];
int main()
{
ios;
int m = read(),n = read();
rep(i,1,m){
a[i] = read();
}
sort(a+1,a+1+m);
long sum = 0;
a[0] = maxnn;
a[m+1] = maxnn;
while(n--){
int temp = read();
int pos = lower_bound(a+1,a+1+m,temp)-a;
//cout << pos << endl;
int ans = min(min(abs(temp-a[pos-1]), abs(temp-a[pos+1])),abs(temp-a[pos]));
//cout << ans << endl;
sum += ans;
}
cout << sum;
return 0;
}