#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iterator>
#include <bitset>
#include <unordered_set>
#include <unordered_map>
//#include <utility>
//#include <memory>
//#include <functional>
//#include <deque>
//#include <cctype>
//#include <ctime>
//#include <numeric>
//#include <list>
//#include <iomanip>

//#if __cplusplus >= 201103L
//#include <array>
//#include <tuple>
//#include <initializer_list>
//#include <forward_list>
//
//#define cauto const auto&
//#else

//#endif

using namespace std;


typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vint;
typedef vector<vector<int> > vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long> > vvll, vvLL;

#define VV(T) vector<vector< T > >

template <class T>
void initvv(vector<vector<T> > &v, int a, int b, const T &t = T()){
    v.assign(a, vector<T>(b, t));
}

template <class F, class T>
void convert(const F &f, T &t){
    stringstream ss;
    ss << f;
    ss >> t;
}


#define reep(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) reep((i),0,(n))
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(),(v).rend()
#define DEBUG
#ifdef DEBUG
#define dump(x)  cout << #x << " = " << (x) << endl;
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
#else
#define dump(x) 
#define debug(x) 
#endif

#define MOD 1000000007LL
#define EPS 1e-8
static const int INF=1<<24;
bool dp[20110][20110];
int foo(int x){
	return x*x;
}
void mainmain(){
	int n;
	cin>>n;
	int ans=0;
	// rep(i,20110) rep(j,20110) dp[i][j]=false;
	rep(i,n){
		int x,y;
		cin>>x>>y;
		bool f=true;
		reep(i,-20,21){
			if(x+i<0) continue;
			reep(j,-20,21){
				if(y+j<0) continue;
				if(dp[x+i][y+j]&&foo(i)+foo(j)<400){
					// cout<<x+i<<" "<<y+j<<endl;
					f=false;
					break;
				}
			}
			if(!f) break;
		}
		// cout<<f<<endl;
		if(dp[x][y]==false&&f) ans++,dp[x][y]=true;
		// ans+=f;
	}
	// int ans=0;
	// rep(i,20110) rep(j,20110) ans+=dp[i][j];
	cout<<ans<<endl;
}


main() {
    mainmain();
}