#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<60;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

int n;
set<int> sx[20001];

int main() {
	cin >> n;
	
	int ans = 0;
	
	REP(i, n) {
		int x, y;
		scanf("%d %d", &x, &y);
		
		bool ok = true;
		
		FOR(j, -20, 21) {
			if (!ok) break;
			
			int nx = x + j;
			
			if (nx >= 0 && nx <= 20000) {
				set<int>::iterator it = sx[nx].lower_bound(y - 20);
				
				while (ok && it != sx[nx].end() && *it <= y + 20) {
					ll d = (x - nx) * (x - nx) + (y - *it) * (y - *it);
					
					if (d < 400) ok = false;
					it++;
				}
			}
		}
		
		if (ok) {
			ans++;
			sx[x].insert(y);
		}
	}
	
	cout << ans << endl;
	
	return 0;
}