#include<stdio.h>
#include<math.h>
#include<algorithm>
using namespace std;
 
#define mid (left + right) / 2
 
const int NMAX = 1505;
const double eps = 1.e-3;
 
struct POINT {
    double x, y;
 
    void read() {
        scanf("%lf%lf", &x, &y);
    }
};
POINT p[NMAX];
 
bool cmp (POINT a, POINT b) {
    if(fabs(a.x - b.x) < eps)
        return a.y < b.y;
    return a.x < b.x;
}
 
int n;
 
bool found (int left, double x, double y) {
    int right;
 
    right = n;
    while(left <= right) {
        if(fabs(p[mid].x - x) < eps) {
            if(fabs(p[mid].y - y) < eps)
                return 1;
 
            if(p[mid].y < y)
                left = mid + 1;
            else
                right = mid - 1;
 
            continue;
        }
 
        if(p[mid].x < x)
            left = mid + 1;
        else
            right = mid - 1;
    }
 
    return 0;
}
 
int main() {
    freopen("triang.in", "r", stdin);
    freopen("triang.out", "w", stdout);
    int i, j, res;
    double xMid, yMid, xDif, yDif, rad;
 
    scanf("%d", &n);
    for(i = 1; i <= n; ++ i)
        p[i].read();
 
    sort(p + 1, p + n + 1, cmp);
 
    rad = sqrt(3) * 0.5;
    res = 0;
    for(i = 1; i <= n; ++ i)
        for(j = i + 1; j <= n; ++ j) {
            xDif = p[j].x - p[i].x;
            yDif = p[i].y - p[j].y;
 
            xMid = (p[i].x + p[j].x) * 0.5;
            yMid = (p[i].y + p[j].y) * 0.5;
 
            if(found(j + 1, xMid + yDif * rad, yMid + xDif * rad))
                ++ res;
            if(found(j + 1, xMid - yDif * rad, yMid - xDif * rad))
                ++ res;
        }
 
    printf("%d\n", res);
    return 0;
}