#include<bits/stdc++.h>
using namespace std;
#include<atcoder/all>
using namespace atcoder;
using ll = long long;
int n;
vector<ll> x,y;
bool is[20001][20001];
vector<int> dx,dy;

bool dist20(int sx,int sy){
	return sx*sx+sy*sy<400;
}

void solve(){
	for(int i = -30;i<30;i++){
		for(int j = -30;j<30;j++){
			if(dist20(i,j)){
				dx.push_back(i);
				dy.push_back(j);
			}
		}
	}
	for(int i = 0;i<n;i++){
		bool canon = true;
		for(int j = 0;j<dx.size();j++){
			int nx = x[i]+dx[j];
			int ny = y[i]+dy[j];
			if(0<=nx&&nx<20001){
				if(0<=ny&&ny<20001){
					if(is[nx][ny]){
						canon = false;
					}
				}
			}
		}
		is[x[i]][y[i]] = canon;
	}
	int ans = 0;
	for(int i = 0;i<20001;i++){
		for(int j = 0;j<20001;j++){
			ans += is[i][j];
		}
	}
	cout<<ans<<endl;
}

signed main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cin >> n;
	x = y = vector<ll>(n);
	for(int i =0;i<n;i++){
		cin >> x[i] >> y[i];
	}
	solve();
}