143行代码爆零了，求查错

#include<stdio.h>
#include<math.h>
struct mon
{
    int x;
    int y;
    int v;
};
int father[10001];
int max(int a,int b)
{
    return a>b?a:b;
}
int find(int x)
{
    if(father[x]!=x)
    father[x]=find(father[x]);
    return father[x];
}
void qsortcommon(int a[],int l,int r)
{
    int i,j,mid,p;
    i=l;
    j=r;
    mid=a[(l+r)/2];
    while(i<=j)
{
    while(a[i]<mid)
    i++;
    while(a[j]>mid)
    j--;
    if(i<=j)
{
    p=a[i];
    a[i]=a[j];
    a[j]=p;
    i++;
    j--;
}
}
    if(l<j)
    qsortcommon(a,l,j);
    if(i<r)
    qsortcommon(a,i,r);
}
void qsort(struct mon a[],int l,int r)
{
    int i,j,mid;
    struct mon p;
    i=l;
    j=r;
    mid=a[(l+r)/2].v;
    while(i<=j)
{
    while(a[i].v<mid)
    i++;
    while(a[j].v>mid)
    j--;
    if(i<=j)
{
    p=a[i];
    a[i]=a[j];
    a[j]=p;
    i++;
    j--;
}
}
    if(l<j)
    qsort(a,l,j);
    if(i<r)
    qsort(a,i,r);
}
inline int read()
{
    int x=0,w=1;
    char ch=getchar();
    while(ch>'9'||ch<'0')
{
    if(ch=='-')
    w=-1;
    ch=getchar();
}
    while(ch<='9'&&ch>='0')
{
    x=(x<<3)+(x<<1)+ch-'0';
    ch=getchar();
}
    return w*x;
}
int main()
{
    struct mon a[10001];
    int o=0,i,j,monkeys[10001],n,x[10001],y[10001],ans=0,s;
    n=read();
    for(i=1;i<=n;i++)
    monkeys[i]=read();
    qsortcommon(monkeys,1,n);
    s=read();
    for(i=1;i<=n;i++)
{
    x[i]=read();
    y[i]=read();
}
    for(i=1;i<=n;i++)
    for(j=1;j<=n;j++)
{
    int tx=x[i]-x[j];
    int ty=y[i]-y[j];
    int ts;
    tx*=tx;
    ty*=ty;
    ts=(int)sqrt(tx+ty);
    o++;
    a[o].x=i;
    a[o].y=j;
    a[o].v=s;
}
    int k;
    qsort(a,1,o);
    int temp=0;
    for(i=1;i<=o;i++)
{
    int r1,r2;
    r1=find(a[i].x);
    r2=find(a[i].y);
    if(r1!=r2)
{
    k=max(s,a[i].v);
    father[r1]=r2;
    k++;
    temp++;
}
    if(temp==n-1)
    break;
}
    for(i=1;i<=n;i++)
    if(monkeys[i]>k)
    ans++;
    else
    break;
    printf("%d\n",ans-1);
    return 0;
}