#include <bits/stdc++.h>
using namespace std;
using LL=long long;
#define rep(i,n) for(int i=0; i<(n); i++)

struct Pos{ LL x,y; };
bool operator<(Pos l,Pos r){ return false; }

int N;
Pos P[1000];
int F[1000]={};
priority_queue<pair<LL,Pos>> V;
LL dist(int a,int b){
  LL dx=P[a].x-P[b].x;
  LL dy=P[a].y-P[b].y;
  return -dx*dx-dy*dy;
}

int main(){
  cin>>N;
  rep(i,N) cin>>P[i].x>>P[i].y;
  rep(i,N) rep(j,i) V.push({dist(i,j),{i,j}});
  int ans=0;
  while(V.size()){
    Pos p=V.top().second; V.pop();
    if(F[p.x]+F[p.y]) continue;
    if(p.x*p.y==0){ F[p.x+p.y]=1; ans++; continue; }
    F[p.x]=F[p.y]=1;
  }
  cout<<ans<<endl;
  return 0;
}