#define _USE_MATH_DEFINES

#include <iostream>
#include <iomanip>

#include <algorithm>
#include <cmath>

#include <string>
#include <array>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>
#include <map>

/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;

#define PII pair<int,int>
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////

bool field[20001][20001];
bool D[21][21];

void fieldSet(int x,int y){//O(400)
	int cX,cY;
	bool flag;
	for(int Y=0;Y<=20;++Y){
		for(int X=0;X<=20;++X){
			flag = D[Y][X];
			if(flag == true ){
cX = x+X;cY = y+Y;if(0<= cY && cY <= 20000 && 0 <= cX && cX <= 20000)field[cY][cX] = flag;
cX = x-X;cY = y+Y;if(0<= cY && cY <= 20000 && 0 <= cX && cX <= 20000)field[cY][cX] = flag;
cX = x+X;cY = y-Y;if(0<= cY && cY <= 20000 && 0 <= cX && cX <= 20000)field[cY][cX] = flag;
cX = x-X;cY = y-Y;if(0<= cY && cY <= 20000 && 0 <= cX && cX <= 20000)field[cY][cX] = flag;
			}
		}
	}
	return;
}
int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    cout << setprecision(10);//

	for(int y=0;y<=20;++y){
		for(int x=0;x<=20;++x){
			if( x*x+y*y >= 400 ){
				D[y][x] = false;
			}else{
				D[y][x] = true;
			}
		}
	}

	int N;
	cin>>N;
	int X,Y;
	int ans = 0;
	rep(i,N){
		cin>>X>>Y;
		if(field[Y][X] == false){
			++ans;
			fieldSet(X,Y);//O(400)
		}
	}
	P(ans);
    return 0;
}