#include <iostream>
#include <vector>
#include <set>
#include <queue>
#include <stack>
#include <math.h>
#include <cassert>
#include <bitset>
#include <map>
#include <algorithm>
#include <iterator>
#include <string>
#include <utility>
#include <numeric>
#include <regex>
#include <complex>
#include <random>
#include <atcoder/all>
using namespace atcoder;
using namespace std;
using ll=long long;
using ull=unsigned long long;
using P=pair<ll,ll>;
template<typename T>using minque=priority_queue<T,vector<T>,greater<T>>;
template<typename T>bool chmax(T &a,const T &b){return (a<b?(a=b,true):false);}
template<typename T>bool chmin(T &a,const T &b){return (a>b?(a=b,true):false);}
template<typename T1,typename T2>ostream &operator<<(ostream &os,const pair<T1,T2>&p){os<<p.first<<' '<<p.second;return os;}
template<typename T1,typename T2>istream &operator>>(istream &is,pair<T1,T2>&p){is>>p.first>>p.second;return is;}
template<typename T> ostream &operator<<(ostream &os,const vector<T> &a){cout<<'{';for(int i=0;i<a.size();i++){cout<<a[i];if(i+1!=a.size())cout<<',';};cout<<'}';return os;}
template<typename T>istream &operator>>(istream &is,vector<T> &a){for(auto &i:a)is>>i;return is;}
#define reps(i,a,n) for(int i=(a);i<(n);i++)
#define rep(i,n) reps(i,0,n)
#define all(x) x.begin(),x.end()
#define pcnt(x) __builtin_popcount(x)
ll myceil(ll a,ll b){return (a+b-1)/b;}
template<typename T1,typename ...T2>
void debug(const T1& x,const T2& ...y){
  #ifdef LOCAL
  cout<<x;
  ((cout<<' '<<y),...);
  cout<<'\n';
  #endif
}
void SOLVE();
int main(){
  #ifdef LOCAL
  clock_t start=clock();
  #endif
  int testcase=1;
  //cin>>testcase;
  for(int i=0;i<testcase;i++){
    SOLVE();
  }
  #ifdef LOCAL
  cout<<"time:";
  cout<<(clock()-start)/1000;
  cout<<"ms\n";
  #endif
}
struct E{
  int u,v;
  int dst;
};
int abs(pair<int,int>a,pair<int,int>b){
  int dx=a.first-b.first,dy=a.second-b.second;
  return dx*dx+dy*dy;
}
bool comp(E a,E b){return a.dst<b.dst;}
void SOLVE(){
  int n;
  cin>>n;
  vector<pair<int,int>>a(n);
  rep(i,n){
    int x,y;
    cin>>x>>y;
    a[i]={x,y};
  }
  dsu uf(n);
  vector<E>edge;
  vector<vector<int>>to(n);
  vector<int>cnt(n,0);
  vector<bool>seen(n,false);
  rep(i,n){
    vector<E>cu;
    rep(j,n)if(i!=j){
      cu.push_back({i,j,abs(a[i],a[j])});
    }
    sort(all(cu),comp);
    edge.insert(edge.end(),cu.begin(),cu.begin()+min<int>(5,cu.size()));
  }
  sort(all(edge),comp);
  for(auto [u,v,dst]:edge){
    if(uf.same(u,v))continue;
    uf.merge(u,v);
    to[u].push_back(v);
    to[v].push_back(u);
    cnt[u]++,cnt[v]++;
  }
  queue<int>que;
  rep(i,n)if(cnt[i]==1)que.push(i);
  vector<pair<int,int>>ans;
  while(!que.empty()){
    int x=que.front();
    que.pop();
    for(auto i:to[x]){
      if(!seen[i]){
        cnt[i]--;
        que.push(i);
        if(!seen[x]){
          ans.push_back({i+1,x+1});
          seen[i]=seen[x]=true;
        }
      }
    }
  }
  cout<<ans.size()<<endl;
  for(auto i:ans)cout<<i<<endl;
}