#pragma GCC target("avx2")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
#include <sys/time.h>

using namespace std;

long long start_time;

void start_clock(){
  struct timeval tv;
  gettimeofday(&tv, NULL);
  start_time=(tv.tv_sec*1000000+tv.tv_usec);
}

long long current_clock(){
  struct timeval tv;
  gettimeofday(&tv, NULL);
  long long current_time=(tv.tv_sec*1000000+tv.tv_usec);
  // cout << current_time-start_time << "(us)\n";
  return current_time-start_time;
}

unsigned long long xor128(){
  static unsigned long long x=123456789,y=362436069,z=521288629,w=88675123;
  unsigned long long t;
  t=(x^(x<<11));x=y;y=z;z=w; return( w=(w^(w>>19))^(t^(t>>8)) );
}

using i128=__int128;
using pll=pair<long long,long long>;

i128 det(long long a,long long b,long long c,long long d){
  i128 l=a; l*=d;
  i128 r=b; r*=c;
  return (l-r);
}

vector<pll> convex_hull(vector<pll> P,bool actsort=true){
    // Copyright (c) 2023 0214sh7
    // https://github.com/0214sh7/library/
    if(P.size()<=2){
        return P;
    }
    vector<pll> H,L,R;
    if(actsort){ sort(P.begin(),P.end()); }

    //下半分
    for(int i=0;i<P.size();i++){
        int j=L.size();
        while(j>=2 && det((L[j-1].first-L[j-2].first),(L[j-1].second-L[j-2].second),(P[i].first-L[j-2].first),(P[i].second-L[j-2].second))<=0){
            L.pop_back();
            j--;
        }
        L.push_back(P[i]);
    }

    //上半分
    for(int i=P.size()-1;i>=0;i--){
        int j=H.size();
        while(j>=2 && det((H[j-1].first-H[j-2].first),(H[j-1].second-H[j-2].second),(P[i].first-H[j-2].first),(P[i].second-H[j-2].second))<=0){
            H.pop_back();
            j--;
        }
        H.push_back(P[i]);
    }

    R=L;
    for(int i=1;i<H.size()-1;i++){
        R.push_back(H[i]);
    }

    return R;
}

pll f(pll a,pll b){
  return {(a.first+b.first)/2,(a.second+b.second)/2};
}

i128 target=500000000000000000;

bool jud(vector<pll> &P){
  int n=P.size();
  for(int i=0;i<n;i++){
    i128 a=P[(i+1)%n].first-P[i].first;
    i128 b=P[(i+1)%n].second-P[i].second;
    i128 c=target-P[i].first;
    i128 d=target-P[i].second;

    if(a*d-b*c < 0){
      return false;
    }
  }
  return true;
}

void shrink(int tg,vector<pll> &p){
  for(int i=0;i<p.size();i++){
    p[i]=f(p[i],p[tg]);
  }
}

using pi=pair<int,int>;

vector<pi> gensuf(int remhd,vector<pll> p){
  int n=p.size();
  vector<int> id(n-1);
  for(int i=0;i<n-1;i++){
    p[i]=p[i+1];
    id[i]=i+1;
  }
  p.pop_back();
  vector<pi> res;

  vector<pair<pll,int>> ppi;
  for(int i=0;i<p.size();i++){
    ppi.push_back({p[i],id[i]});
  }
  sort(ppi.begin(),ppi.end());
  for(int i=0;i<p.size();i++){
    p[i]=ppi[i].first;
    id[i]=ppi[i].second;
  }

  for(int hd=0;hd<remhd;hd++){
    int tg=-1;
    i128 gp=1e37;
    for(int i=0;i<p.size();i++){
      vector<pll> up=p;
      shrink(i,up);
      vector<pll> htg;
      for(int j=0;j<p.size();j++){
        if(i==j){continue;}
        htg.push_back(up[j]);
      }
      vector<pll> ch=convex_hull(htg,false);
      if(jud(ch)){
        i128 gx=0,gy=0;
        for(auto &nx : ch){
          gx+=nx.first;
          gy+=nx.second;
        }
        gx/=ch.size();
        gy/=ch.size();
        i128 gd=(gx-target)*(gx-target)+(gy-target)*(gy-target);
        if(gp > gd){
          gp=gd;
          tg=i;
        }
      }
    }
    if(tg==-1){break;}

    shrink(tg,p);
    res.push_back({0,id[tg]});
    for(int i=tg;i<p.size();i++){
      p[i]=p[i+1];
      id[i]=id[i+1];
    }
    p.pop_back();
    id.pop_back();
  }

  reverse(res.begin(),res.end());
  return res;
}

void simu(vector<pi> &op,vector<pll> &p){
  for(auto &nx : op){
    p[nx.first]=f(p[nx.first],p[nx.second]);
    p[nx.second]=p[nx.first];
  }
}

int main(){
  start_clock();
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int n;
  cin >> n;
  vector<pll> p(n);
  for(int i=0;i<n;i++){
    long long x,y;
    cin >> x >> y;
    p[i].first=x;
    p[i].second=y;
  }

  vector<pi> res;
  for(int work=0;work<1000;work++){
    res=gensuf(50,p);
  }

  cout << res.size() << "\n";
  for(auto &nx : res){
    cout << nx.first+1 << " " << nx.second+1 << "\n";
  }

  // simu(res,p);
  // for(auto &nx : p){
  //   long long ox=nx.first;
  //   long long oy=nx.second;
  //   cout << ox << " " << oy << "\n";
  // }
  return 0;
}