#include <bits/stdc++.h>
#define rep(i, a) for (int i = 0; i < (a); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) for (int i = (a) - 1; i >= 0; i--)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 7;

const ll U = 100;
const int W = 22000 / U;
const int H = 22000 / U;
vector<int> bucket[W][H];
ll xs[100000], ys[100000];

ll sq(ll x) {
    return x * x;
}

bool intersect(int i, int j) {
    return sq(xs[j] - xs[i]) + sq(ys[j] - ys[i]) < sq(20);
}

void put(int k) {
    ll x = xs[k];
    ll y = ys[k];
    int bx = x / U;
    int by = y / U;

    bool b = false;

    rep2 (dx, -1, 2) rep2 (dy, -1, 2) {
        int nx = bx + dx;
        int ny = by + dy;

        for (int i : bucket[nx][ny]) {
            if (intersect(k, i)) {
                b = true;
            }
        }
    }

    if (!b) {
        bucket[bx][by].push_back(k);
    }
}

int main() {
    int N;
    cin >> N;
    rep (i, N) {
        cin >> xs[i] >> ys[i];
        xs[i] += U;
        ys[i] += U;
    }

    rep (i, N) put(i);

    int ans = 0;
    rep (i, W) rep (j, H) ans += bucket[i][j].size();
    cout << ans << endl;
}