#include <iostream>
#include <set>
#include <map>
using namespace std;
bool is_overlap(int x0, int y0, int x1, int y1)
{
#define sq(x) ((x)*(x))
#define dist(a, b, c, d) (sq(a-c)+sq(b-d))
    return dist(x0, y0, x1, y1)<400;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n;
    while (cin>>n) {
        map<int, set<int>> a;
        while (n--) {
            int x, y; cin>>x>>y;
            bool overlap=false;
            for(auto i=a.lower_bound(x-20);i!=a.end();++i) {
                if (i->first-20>=x+20) break;
                auto& b=i->second;
                for(auto j=b.lower_bound(y-20);j!=b.end();++j) {
                    if (*j-20>=y+20) break;
                    if (overlap=is_overlap(x, y, i->first, *j)) break;
                }
                if (overlap) break;
            }
            if (!overlap) a[x].insert(y);
        }
        int res=0;
        for(auto&v: a) res+=v.second.size();
        cout<<res<<endl;
    }
}