这么写咋错了，我理解错题目了？

#include<bits/stdc++.h>
using namespace std;
const int N=100005;
int n,m,a[N];
int find(int x)
{
    int l=1,r=n,mid,ans;
    while (l<=r){
        mid=l+r>>1;
        if (a[mid]<=x){
            ans=mid;
            l=mid+1;
        }
        else r=mid-1;
    }
    return ans;
}
int main()
{
    cin>>n>>m;
    for (int i=1;i<=n;i++) scanf("%d",a+i);
    sort(a+1,a+n+1);
    int ans=0;
    for (int i=1;i<=m;i++){
        int x;
        scanf("%d",&x);
        int pos=find(x),minn=2e9;
        for (int j=max(1,pos-2);j<=min(n,pos+2);j++)
            minn=min(minn,abs(a[j]-x));
        ans+=minn;
    }
    cout<<ans<<endl;
    return 0;
 }