#include <iostream>#include <cmath>#include <algorithm>#include <stdio.h>using namespace std;const int N=1010;const int M=40010;struct m_point{int x,y;};m_point s[N];int m_hash[M],next[N],n;bool cmp(const m_point &p1,const m_point &p2){if(p1.x < p2.x)return true;if((p1.x == p2.x) && (p1.y < p2.y))return true;return false;}bool isExist(int x,int y){int value=abs(x+y);int index=m_hash[value];while(-1 != index)    {if((s[index].x == x) && (s[index].y == y))return true;        index=next[index];    }return false;}int main(){int i,j,value,new_x,new_y,ans=0;    m_point tmp;while(scanf("%d",&n) && n)    {        ans=0;        memset(next,-1,sizeof(next));        memset(m_hash,-1,sizeof(m_hash));for(i=0;i<n;++i)            scanf("%d%d",&s[i].x,&s[i].y);        sort(s,s+n,cmp);for(i=0;i<n;++i)        {    　//hash函数是采用的两个坐标的和，和相同的用类似与链表连接起来            value=abs(s[i].x+s[i].y);            next[i]=m_hash[value];//技巧和图的邻接表存储方式相同            m_hash[value]=i;        }//         for(i=0;i<n;++i)//             cout<<s[i].x<<" "<<s[i].y<<'\t';//         cout<<endl;        for(i=0;i<n;++i)        {for(j=i+1;j<n;++j)            {                tmp.x=s[j].x-s[i].x;                tmp.y=s[j].y-s[i].y;                new_x=s[i].x+tmp.y;                new_y=s[i].y-tmp.x;if(!isExist(new_x,new_y))continue;                new_x=s[j].x+tmp.y;                new_y=s[j].y-tmp.x;if(!isExist(new_x,new_y))continue;                ++ans;            }        }        printf("%d\n",ans/2);    }return 0;}

#include <iostream>#include <algorithm>#include <stdio.h>using namespace std;const int N=2002;struct m_point{int x,y;};int n;m_point p[N];bool cmp(const m_point &p1,const m_point &p2){if(p1.x < p2.x)return true;if((p1.x == p2.x) && (p1.y < p2.y))return true;return false;}bool find_point(m_point &t){int left=0,right=n,mid;while(left<=right)    {        mid=(left+right)>>1;if((p[mid].x == t.x) && (p[mid].y == t.y))return true;if(cmp(t,p[mid]))            right=mid-1;else            left=mid+1;    }return false;}

int main(){int i,j,ans;    m_point tmp,new_node;while(scanf("%d",&n) != EOF)    {for(i=0;i<n;++i)            scanf("%d%d",&p[i].x,&p[i].y);        sort(p,p+n,cmp);        ans=0;for(i=0;i<n;++i)        {for(j=i+1;j<n;++j)            {                tmp.x=p[j].x-p[i].x;                tmp.y=p[j].y-p[i].y;                new_node.x=p[i].x+tmp.y;                new_node.y=p[i].y-tmp.x;if(!find_point(new_node))continue;                new_node.x=p[j].x+tmp.y;                new_node.y=p[j].y-tmp.x;if(!find_point(new_node))continue;                ++ans;            }        }        printf("%d\n",ans/2);    }return 0;}