poj 2002 Squares

#include <iostream>
#include <algorithm>
#include <cstdio>
using namespace std;
struct point
{
int x,y;
}p[1001],tmp;
int cmp(point a, point b)
{
if(a.x == b.x)
return a.y < b.y;
return a.x < b.x;
}
int main(void)
{
int n;
while(scanf("%d",&n) != EOF && n)
{
int i,j,ans=0;
for(i=0; i<n; i++)
scanf("%d%d",&p[i].x,&p[i].y);
sort(p,p+n,cmp);
for(i=0; i<n; i++)
for(j=i+1; j<n; j++)
{
tmp.x = p[i].x + p[j].y - p[i].y;
tmp.y = p[i].y -(p[j].x - p[i].x);
if(!binary_search(p,p+n,tmp,cmp))
continue;
tmp.x = p[j].x + p[j].y - p[i].y;
tmp.y = p[j].y - (p[j].x - p[i].x);
if(!binary_search(p,p+n,tmp,cmp))
continue;
ans++;
}
printf("%d/n",ans/2);
}
return 0;
}