/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.05.22 23:28:25
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    int n;cin >> n;
    vector<vector<bool>> g(20001,vector<bool>(20001,false));
    int ans = 0;
    vector<int> dx,dy;
    for (int i = -20; i <= 20; i++) {
        for (int j = -20; j <= 20; j++) {
            if (i * i + j * j < 400) {
                dx.push_back(i);
                dy.push_back(j);
            }
        }
    }
    for (int i = 0; i < n; i++) {
        int a,b;cin >> a >> b;
        if (g[a][b]) continue;
        for (int k = 0; k < dx.size(); k++) {
            int x = a + dx[k], y = b + dy[k];
            if (x >= 0 && x <= 20000 && y >= 0 && y <= 20000) {
                g[x][y] = true;
            }
        }
        ans++;
    }
    cout << ans << endl;
    return 0;
}