#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max() / 32 * 15 + 208;

int main() {
    int n;
    cin >> n;
    vector<ll> x(n), y(n);
    for (int i = 0; i < n; ++i) {
        cin >> x[i] >> y[i];
    }
    vector<tuple<ll, ll, ll>> v;
    for (int i = 0; i < n; ++i) {
        for (int j = i+1; j < n; ++j) {
            v.emplace_back((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]), i, j);
        }
    }
    sort(v.begin(),v.end());
    vector<int> alive(n, 1);
    for (auto [cost, a, b] : v) {
        if(alive[a] != 1 || alive[b] != 1) continue;
        if(a == 0) alive[b] = 0;
        else if(b == 0) alive[a] = 0;
        else {
            alive[a] = alive[b] = -1;
        }
    }
    int ans = 0;
    for (int i = 0; i < n; ++i) {
        if(alive[i] == 0) ans++;
    }
    cout << ans << "\n";
    return 0;
}