#pragma GCC optimize "O3"
#pragma GCC target "tune=native"
#pragma GCC target "avx"
#include <cstdio>
#include <algorithm>
#include <thread>
#define repeat(i,n) for (int i = 0; (i) < int(n); ++(i))
using namespace std;
template <class T> inline T sq(T x) { return x*x; }
constexpr int max_n = 100000;
int x[max_n];
int y[max_n];
bool is_removed[max_n];
int main() {
    int n; scanf("%d", &n);
    repeat (i,n) scanf("%d%d", &x[i], &y[i]);
    thread th[4];
    th[0] = thread([&]() {
    });
    repeat (i,n) {
        int acc = 0;
        repeat (j,i) {
            acc += not is_removed[j] and sq(x[j] - x[i]) + sq(y[j] - y[i]) < sq(10 + 10);
        }
        is_removed[i] = acc;
    }
    int cnt = count(is_removed, is_removed + n, false);
    printf("%d\n", cnt);
    return 0;
}