#include<bits/stdc++.h>
using namespace std;

int n;
int vis[605][605];

struct point
{
    int x,y;
    bool operator<(const point& rhs)const
    {
        return x<rhs.x || x==rhs.x&&y<rhs.y;
    }
}p[505];

int main()
{
    while(~scanf("%d",&n))
    {
        memset(vis,0,sizeof(vis));
        int ans=0;
        for(int i=0;i<n;i++)
        {
            scanf("%d%d",&p[i].x,&p[i].y);
            p[i].x+=300,p[i].y+=300;
            vis[p[i].x][p[i].y]=1;
        }
        sort(p,p+n);
        for(int i=0;i<n;i++)
            for(int j=i+1;j<n;j++)
            {
                point a=p[i],b=p[j];
                int dx=b.x-a.x;
                int dy=b.y-a.y;
                point c,d;
                c.x=a.x-dy,c.y=a.y+dx;
                d.x=b.x-dy,d.y=b.y+dx;
                if(vis[c.x][c.y]&&vis[d.x][d.y]) ans++;
            }
        printf("%d\n",ans/2);
    }
}