#include <bits/stdc++.h>
using namespace std;

#define lp(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, n) lp(i, 0, n)
#define rlp(i, a, b) for (int i = (int)(b) - 1; i >= (int)(a); i--)
#define rrep(i, n) rlp(i, 0, n)

#define mp make_pair
#define mt make_tuple
#define pb push_back
#define eb emplace_back
#define all(c) begin(c), end(c)

typedef long long ll;
typedef unsigned long long ull;

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};

const int MOD = 1e9 + 7;
const int INF = 1 << 28;
const ll INFLL = 1ll << 60;

template<typename T>
inline void unique(T &c){
	sort(all(c));
	c.erase(unique(all(c)), end(c));
}

typedef pair<int, int> P;

int sq(int a){ return a * a; }

vector<P> ds;
int n;
set<P> st;

int main()
{
	lp(i, -22, 22) lp(j, -22, 22){
		if (sq(i) + sq(j) < sq(20)){
			ds.push_back(P(i, j));
		}
	}

	cin >> n;
	rep(i, n){
		int x, y;
		cin >> x >> y;
		bool f = true;
		for (P d : ds){
			P np = P(x + d.first, y + d.second);
			if (st.count(np)) f = false;
		}
		if (f) st.insert(P(x, y));
	}

	cout << st.size() << endl;
}