#include <cstdio>
#include <algorithm>
#include <cmath>
#define MOD 1000
using namespace std;
int n, Sol;
double eps=0.00001;
struct elem{
    double x, y;
}a[1002];
inline bool cmp(elem x, elem y){
    if(x.x != y.x)
        return x.x < y.x;
    if(x.y != y.y)
        return x.y < y.y;
}
inline bool CMP(double x, double y){
    if(fabs(x - y) <= eps) return 1;
}
inline bool CBIN(double x, double y){
    int st = 1, dr = n;
    while( st <= dr )
    {
        int mid = ( st + dr ) / 2;
        if( !CMP(a[mid].x, x ) ){
            if( a[mid].x > x ) dr = mid - 1;
                    else st = mid + 1;
        }
        else {
            if( !CMP( a[mid].y, y ) ){
                if( a[mid].y > y ) dr = mid - 1;
                    else st = mid + 1;
            }
            else return 1;
        }
    }
    return 0;
}
inline void Solve(double x1, double y1, double x2, double y2){
    double mijx = (x1 + x2) / 2, mijy = (y1 + y2) / 2;
    double dx = fabs(mijx - x1), dy = fabs(mijy - y1);
    if(y1 < y2){
        double x3 = mijx + dy, y3 = mijy - dx;
        double x4 = mijx - dy, y4 = mijy + dx;
        if(CBIN(x3, y3) == 0) return ;
        if(CBIN(x4, y4) == 0) return ;
        ++Sol; return ;
    }
    double x3 = mijx - dy, y3 = mijy - dx;
    double x4 = mijx + dy, y4 = mijy + dx;
    if(CBIN(x3, y3) == 0) return ;
    if(CBIN(x4, y4) == 0) return ;
    ++Sol; return ;
}

 main()
{
    freopen("patrate3.in", "r", stdin);
    freopen("patrate3.out", "w", stdout);
    scanf("%d", &n);
    for(int i = 1; i <= n ; ++i)
        scanf("%lf%lf", &a[i].x, &a[i].y);
    sort(a + 1, a + n + 1, cmp);
    for(int i = 1; i < n; ++i){
        for(int j = i + 1; j <= n ; ++j){
            double x1 = a[i].x, y1 = a[i].y;
            double x2 = a[j].x, y2 = a[j].y;
            Solve(x1, y1, x2, y2);
        }
    }
    printf("%d", Sol / 2);
    return 0;
}