#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) ){
                                dist.push_back(point(x,y));
                        }
                }
        }
        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;
                                if(m.count(point(xx,yy))){
                                    int mapped = m[point(xx,yy)];
                                    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;
}