#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstring>
#include <deque>
#include <functional>
#include <iostream>
#include <iomanip>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <cstdint>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
#define MP make_pair
#define PB push_back
#define inf 1000000007
#define rep(i,n) for(int i = 0; i < (int)(n); ++i)
#define all(x) (x).begin(),(x).end()

template<typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val){
    std::fill( (T*)array, (T*)(array+N), val );
}
 
template<class T> inline bool chmax(T &a, T b){
    if(a<b){
        a = b;
        return true;
    }
    return false;
}

template<class T> inline bool chmin(T &a, T b){
    if(a>b){
        a = b;
        return true;
    }
    return false;
}

int main(){
    int n;
    cin >> n;
    vector<ll> a(n),b(n);
    rep(i,n)cin >> a[i] >> b[i];
    priority_queue<pair<ll,pair<int,int> > > pq;
    int s = 0;
    vector<bool> p(n);
    rep(i,n){
        rep(j,i){
            pq.push(MP(-(a[i]-a[j])*(a[i]-a[j])-(b[i]-b[j])*(b[i]-b[j]),MP(i,j)));
        }
    }

    while(!pq.empty()){
        auto x = pq.top();
        pq.pop();
        if(x.second.second==0){
            if(!p[x.second.first]){
                s++;
                p[x.second.first] = 1;
            }
        }else{
            if(!p[x.second.first]){
                if(!p[x.second.second]){
                    p[x.second.first] = 1;
                    p[x.second.second] = 1;
                }
            }
        }
    }
    cout << s << endl;
    return 0;
}