#include<iostream>
#include<stdio.h>
#include<cmath>
using namespace std;
FILE *f=fopen("trapez.in","r");
FILE *g=fopen("trapez.out","w");
struct coord
{
    int x,y;
}v[1001];
struct dr
{
    float l;
    int x,y;
}a[501501];
int n,i,j,k=0,nr=0;
int main()
{
    fscanf(f,"%d",&n);
    for(i=1;i<=n;i++)fscanf(f,"%d%d",&v[i].x,&v[i].y);
    for(i=1;i<n;i++)for(j=i+1;j<=n;j++)
    {
        k++;
        a[k].x=v[j].x-v[i].x;
        a[k].y=v[j].y-v[i].y;
        a[k].l=sqrt(a[k].x*a[k].x+a[k].y*a[k].y);
    }
    for(i=1;i<k;i++)for(j=i+1;j<=k;j++)if(a[i].x*a[j].y==a[i].y*a[j].x)
    {
        nr++;
        if(a[i].l==a[j].l)nr++;
    }
    fprintf(g,"%d",nr);
    fclose(f);
    fclose(g);
}