#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <set>
#include <map>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
#define loop(i,a,b) for(int i=(a);i<int(b);i++)
#define rep(i,b) loop(i,0,b)
#define all(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;

//#define int ll
//#define endl "\n"

template<typename Type, unsigned N, unsigned Last>
struct tuple_printer
{
    static void print(std::ostream& out, const Type& value)
    {
        out << std::get<N>(value) << ", ";
        tuple_printer<Type, N + 1, Last>::print(out, value);
    }
};
template<typename Type, unsigned N>
struct tuple_printer < Type, N, N >
{
    static void print(std::ostream& out, const Type& value)
    {
        out << std::get<N>(value);
    }
};
template<typename... Types>
std::ostream& operator<<(std::ostream& out, const std::tuple<Types...>& value)
{
    out << "(";
    tuple_printer<std::tuple<Types...>, 0, sizeof...(Types)-1>::print(out, value);
    out << ")";
    return out;
}

#ifdef DEBUG
#define dump(...) (cerr << #__VA_ARGS__ << " = " << make_tuple(__VA_ARGS__) << " [" << __LINE__ << "]" << endl)
#else
#define dump(...)
#endif

int main(){
    set<pair<int, int>> exi;
    int n;
    cin >> n;
    int ans = 0;
    rep(i, n){
        int x, y;
        cin >> x >> y;
        bool hit = false;
        for (int iy = y - 15; !hit && iy <= y + 15; iy++){
            for (int ix = x - 15; !hit && ix <= x + 15; ix++){
                if (exi.count(make_pair(ix, iy))==0) continue;
                int dx = ix - x;
                int dy = iy - y;
                int d2 = dx*dx + dy*dy;
                if (d2 < 400) hit = true;
            }
        }
        if (!hit) {
            ans++;
            exi.emplace(x, y);
        }
    }
    cout << ans << endl;
}