#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 (double x, double y) {
    int left, right;

    left = 1;
    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 = fabs(p[i].x - p[j].x);
            yDif = fabs(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(xMid + yDif * rad, yMid + xDif * rad))
                ++ res;
            if(found(xMid - yDif * rad, yMid - xDif * rad))
                ++ res;
        }

    printf("%d\n", res / 2);
    return 0;
}