#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> point;

const int MAXN = 50010;

map<point,int> m;
point v[MAXN];
int vis[MAXN];
vector<int> adj[MAXN];

bool euclidean_dist(int x,int y){
    return (hypot(x,y) <= 5.0);
}

int main(){
    vector<point> dist;
    for(int x = -5 ; x <= 5 ; x++){
        for(int y = -5 ; y <= 5 ; y++){
            if(euclidean_dist(x,y) && (x|y) ){
                // cout << "1" << " ";
                dist.push_back(point(x,y));
            }
            // else {
            //  cout << "0" << " ";
            // }
        }
        cout << endl;
    }
    int n,x,y;
    while(scanf("%d",&n)==1){
        m.clear();
        for(int i = 1; i <= n; i++){
            scanf("%d%d",&x,&y);
            v[i] = point(x,y);
            m[point(x,y)] = i;
            adj[i].clear();
        }
        for (int i = 1; i <= n; i++){
            x = v[i].first;
            y = v[i].second;
            for(int j = 0 ; j < dist.size() ; j++){
                int xx = x + dist[j].first;
                int yy = y + dist[j].second;
                int mapped = m[point(xx,yy)];
                if(mapped){
                    adj[i].push_back(mapped);
                    adj[mapped].push_back(i);
                }
            }
        }
        memset(vis,0,sizeof vis);
        int ans = 0;
        for(int i = 1 ; i <= n; i++){
            if(!vis[i]){
                int one = 1;
                int two = 0;
                queue<int> q;
                q.push(i);
                vis[i] = 1;
                while(!q.empty()){
                    int from = q.front();q.pop();
                    for(int j = 0 ; j < adj[from].size() ; j++){
                        int to = adj[from][j];
                        if(!vis[to]){
                            q.push(to);
                            vis[to] = (vis[from] == 1) ? 2 : 1;
                            one += (vis[to] == 1);
                            two += (vis[to] == 2);
                        }
                    }
                }
                ans += min(one,two);
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}