#include <cmath>
#define x first
#define y second
#include <fstream>
#include <vector>
using namespace std;

ifstream fin ("patrate3.in");
ofstream fout ("patrate3.out");

const int Dim = 1001,mod = 636013;
const double eps = 1e-8;
typedef pair <  int,  int > Punct;

int n,cnt;
Punct A[Dim];
vector < Punct > H[mod];

bool Egal(Punct X, Punct Y);
void Insert(Punct X);
bool Find(Punct X);

int main() {
	
	fin >> n;
	double x,y;
	for ( int i = 1; i <= n; ++i) {
		fin >> x >> y;
		x *= 1000;
		y *= 1000;
		A[i] ={ x,y};
		Insert(A[i]);
	}
	for ( int i = 1; i < n; ++i)
		for ( int j = i + 1; j <= n; ++j) {
			Punct Mid,X,Y;
			Mid = {(A[i].x + A[j].x) / 2., (A[i].y + A[j].y) / 2.};
			X = {Mid.x - (A[j].y - Mid.y), Mid.y + (A[j].x - Mid.
				x)};
			Y = {Mid.x + (A[j].y - Mid.y), Mid.y - (A[j].x - Mid.x)};
			if ( Find(X)and Find(Y))
					++cnt;	
			}
	fout << cnt/2;
}

bool Find(Punct X) {
      
    int i = X.x % mod;
    if ( i < 0)
		i += mod;
    for ( const auto & j : H[i])
        if ( j == X ) 
            return 1;
    return 0;
}
  
void Insert(Punct X){
   
    int i = X.x % mod;
	if ( i < 0)
		i += mod;
  
    H[i].push_back(X);
}