#include <cstdio>
#include <algorithm>
#include <cmath>

#define maxn 1500
#define eps 0.001

FILE *in = fopen("triang.in","r"), *out = fopen("triang.out","w");

int n;
int cnt;
struct pct
{
    double x, y;
};

pct a[maxn];

bool operator<(const pct &t, const pct &d)
{
    return d.x - t.x >= eps;
}

void read()
{
    fscanf(in, "%d", &n);

    for ( int i = 0; i < n; ++i )
        fscanf(in, "%lf %lf", &a[i].x, &a[i].y);
}

int main()
{
    read();
    std::sort(a, a+n);

    for ( int i = 0; i < n; ++i )
        for ( int j = i + 1; j < n; ++j )
            for ( int k = j + 1; k < n; ++k )
                if ( a[k].x - a[j].x == a[j].x - a[i].x )
                    if ( sqrt((a[k].x - a[j].x)*(a[k].x - a[j].x) + (a[k].y - a[j].y)*(a[k].y - a[j].y)) )
                        ++cnt;

    fprintf(out, "%d\n", cnt);


	return 0;
}