#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;

const int mod = 666013;
const int NMax = 1002;

struct point{
int x,y;
}points[NMax];



vector<point> H[666013];

int hash_func(point X)
{
    int x,y;
    if(X.x < 0 )
        x=-X.x;
    else
        x=X.x;
    if(X.y < 0)
        y=-X.y;
    else
        y=X.y;
    return (x+y)%mod;
}

void Hash_Insert(point X)
{
    int where = hash_func(X);
    H[where].push_back(X);
}
int Hash_Find(point X)
{
    int where = hash_func(X);
    vector<point>::iterator it;
    for(it = H[where].begin(); it != H[where].end(); it++ )
    {
        if(it->x == X.x && (it->y = X.y))
            return 1;
    }
    return 0;
}

int getNumber(char c[])
{
    int number=0;
    int sign = 1;
    int i = 0;
    if(c[i]=='-')
     {
         sign = -1;
         i++;
     }
     for(;c[i];i++)
     {
         if(c[i]>='0' && c[i] <='9')
         {
            number = number*10 + c[i]-'0';
         }
     }
     number = number * sign;
}

int main()
{
    int n,i,j;
    freopen("patrate3.in","r",stdin);
    freopen("patrate3.out","w",stdout);
    scanf("%d\n",&n);
    point newpoint;
    char s[28];
    for(i = 1;i <= n;i++)
    {
        scanf("%s",s);
        newpoint.x=getNumber(s);
        scanf("%s",s);
        newpoint.y=getNumber(s);
        //cout<<newpoint.x<<" "<<newpoint.y<<" "<<hash_func(newpoint)<<"\n";
        Hash_Insert(newpoint);
        points[i]=newpoint;
    }
//    //51.5700 10.9400
    int sum = 0;
    for(i=1;i<=n;i++)
    {
        int x1 = points[i].x;
        int y1 = points[i].y;
        for(j=i+1;j<=n;j++)
        {
            int x2 = points[j].x;
            int y2 = points[j].y;
            int mx = (x1 + x2) / 2;
            int my = (y1 + y2) / 2;
            int x3 = mx - (y1 - my);
            int y3 = my + (x1 - mx);
            int x4 = mx + (y1 - my);
            int y4 = my - (x1 - mx);
            point point1;
            point point2;
            point1.x = x3;
            point1.y = y3;
            point2.x = x4;
            point2.y = y4;
            if(Hash_Find(point1) && Hash_Find(point2))
            {
                //printf("%d %d %d %d \n", point1.x,point1.y,point2.x,point2.y);
                sum++;
            }

        }
    }
    cout<<sum/2;

}