#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int N;
vi X, Y;
vi dx, dy;

void solve(){
    bitset<20001 * 20001> xy;
    rep(i, N){
        bool ok = true;
        rep(j, sz(dx)){
            int x = X[i] + dx[j];
            int y = Y[i] + dy[j];
            if(x >= 0 && x <= 20000 && y >= 0 && y <= 20000){
                int k = x * 20001 + y;
                if(xy[k]){
                    ok = false;
                    break;
                }
            }
        }
        if(ok){
            int k = X[i] * 20001 + Y[i];
            xy[k] = 1;
        }
    }
    
    cout << xy.count() << endl;
}

int main(){
    for(int i = -19; i < 20; ++i){
        for(int j = -19; j < 20; ++j){
            if(i*i+j*j < 400){
                dx.push_back(i);
                dy.push_back(j);
            }
        }
    }

    while(cin >> N){
        X.resize(N); Y.resize(N);
        rep(i, N)scanf("%d%d", &X[i], &Y[i]);
        solve();
    }
}