#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
}
void SOLVE(){
  int n;
  cin>>n;
  vector<pair<int,int>>a(n);
  cin>>a;
  dsu uf(n);
  vector<pair<int,int>>edge;
  vector<vector<int>>to(n);
  vector<int>cnt(n,0);
  vector<bool>seen(n,false);
  rep(i,n-1)reps(j,i+1,n){
    edge.push_back({i,j});
  }
  sort(all(edge),[&](pair<int,int> g,pair<int,int> h)->bool {
    if(0>g.first)exit(0);
    if(0>g.second)exit(0);
    if(0>h.first)exit(0);
    if(0>h.second)exit(0);
    int sx=a.at(g.first).first-a.at(g.second).first,sy=a.at(g.first).second-a.at(g.second).second;
    int gx=a.at(h.first).first-a.at(h.second).first,gy=a.at(h.first).second-a.at(h.second).second;
    // int sx=a[g.first].first-a[g.second].first,sy=a[g.first].second-a[g.second].second;
    // int gx=a[h.first].first-a[h.second].first,gy=a[h.first].second-a[h.second].second;
    return sx*sx+sy*sy<gx*gx+gy*gy;
  });
  for(auto [u,v]: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]--;
        if(!seen[x]){
          seen[x]=true;
          seen[i]=true;
          ans.push_back({i+1,x+1});
        }
      }
    }
  }
  cout<<ans.size()<<endl;
  for(auto i:ans)cout<<i<<endl;
}