#include <algorithm>
#include <bitset>
#include <chrono>
#include <cmath>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using ll = long long;
using vll = std::vector<ll>;
using namespace std;
#define REP(i, x, n) for(int i = x; i < (n); i++)
#define rep(i, n) REP(i, 0, n)
const ll MOD = 1000000007;
template<class T> void gi(T &x){
  int minus=0; x=0; char c=getchar();
  for(;c<'0'||c>'9'; c=getchar()) minus|=(c=='-');
  for(;c>='0'&&c<='9'; c=getchar()) x=(x<<1)+(x<<3)+(c^48);
  if(minus) x=-x;
}
int main() {
  int n; gi(n);
  vector<pair<int,int>> xy;
  rep(i,n){
    int x,y; gi(x);gi(y);
    xy.push_back({x,y});
  }
  vector<bool> chk(n);
  auto getD = [&](vector<pair<int,int>>& vec, int id1, int id2){
    return sqrt((vec[id1].first-vec[id2].first)*(vec[id1].first-vec[id2].first)
      +(vec[id1].second-vec[id2].second)*(vec[id1].second-vec[id2].second));
  };
  vector<vector<double>> v(n);
  struct D{
    double d; int x; int y;
  };
  auto cmpD = [](D& l, D& r){
    return l.d > r.d;
  };
  priority_queue<D,vector<D>,decltype(cmpD)> q{cmpD};
  REP(i,0,n)REP(j,i+1,n){
    q.push({getD(xy,i,j),i,j});
  }
  int ans = 0;
  while(!q.empty()){
    D target = q.top(); q.pop();
    if(target.x == 0){
      if(chk[target.y] == false){
        ans++;
        chk[target.y] = true;
      }
    }
    else if(chk[target.x] || chk[target.y]){
    }else{
      chk[target.x] = true;
      chk[target.y] = true;
    }
  }
  printf( "%d\n", ans );
  
  return 0;
}