求助，最后一点过不去

一开始没有开longlong，后来一气之下把所有数据全开longlong了，但是最后一点还是过不去

#include <stdio.h>
#include <stdlib.h>
long long m,n;
long long cmp(const void *a,const void *b)
{
    return *(long long *)a-*(long long *)b;
}
long long bisearch(long long school[],long long x)
{
    long long res;
    long long l=0,r=m-1;
    res=school[r]-school[l];
    while(l<=r)
    {
        long long mid=(l+r)/2;
        if(school[l]==x)    return 0;
        if(school[r]==x)    return 0;
        if(school[mid]==x)  return 0;
        if(school[mid]>x)
        {
            if(res>school[mid]-x)   res=school[mid]-x;
            r=mid-1;
        }
        else if(school[mid]<x)
        {
            if(res>x-school[mid])   res=x-school[mid];
            l=mid+1;
        }
    }
    return res;
}
int main()
{
    scanf("%lld%lld",&m,&n);
    long long ans=0;
    long long school[m],stu[n];
    long long i,j;
    for(i=0;i<m;i++)    scanf("%lld",&school[i]);
    for(i=0;i<n;i++)    scanf("%lld",&stu[i]);
    qsort(school,m,sizeof(long long),cmp);
    for(i=0;i<n;i++)
    {
        long long temp;
        temp=bisearch(school,stu[i]);
        ans+=temp;
    }
    printf("%lld",ans);
    return 0;
}