#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int n;
    cin >> n;

    vector<ll> x(n), y(n);
    map<ll, vector<int> > memo;
    int ans = 0;
    for (int i = 0; i < n; i++) {
        cin >> x[i] >> y[i];
        auto it = memo.upper_bound(x[i] - 20);

        bool f = true;
        while (it != memo.end()) {
            if (it->first >= x[i] + 20) break;

            auto& v = it->second;
            int jj = 0;
            while (jj < v.size()) {
                int j = v[jj];

                ll dx = x[i] - x[j];
                ll dy = y[i] - y[j];
                ll r2 = dx * dx + dy * dy;
                if (r2 >= 400) {
                    ++jj;
                    continue;
                }

                f = false;
                break;
            }
            if (!f) break;
            ++it;
        }

        if (f) {
            ++ans;
            memo[x[i]].push_back(i);
        }
    }

    cout << ans << newl;
    return 0;
}