能帮我看看吗哥哥们

哪里错啦

#include<bits/stdc++.h>
using namespace std;
#define N (int)1e8
int a[N],b[N];
int main(){
    int n,m,i,j,sum=0;
    cin>>n>>m;
    for(i=0;i<n;i++){
        cin>>a[i];
    }
    for(j=0;j<m;j++){
        cin>>b[j];
    }
    sort(a,a+n);
    //int l,r,mid;
    for(i=0;i<m;i++){
        int l=0,r=n;
        while(l<r){
            int mid=(l+r)/2;
            if(a[mid]<=b[i]){
                l=mid+1;
            }
            else{
                r=mid-1;
            }
        }
        if(b[i]<=a[0]){
            sum+=a[0]-b[i];
        }
        else{
            sum+=min(abs(a[l-1]-b[i]),abs(a[l]-b[i]));
        }
    }
    cout<<sum;
    return 0;
}