#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;
}

using pl=pair<long long,long long>;

long long target=500000000000000000;

double score(pl a){
  long long mg=max(abs(a.first-target),abs(a.second-target));
  return 1.0-0.05*log10(mg+1);
}

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

typedef struct{
  vector<pl> card;
  vector<int> hand;
}Game;

long long eval(Game &g){
  long long g1=abs(g.card[0].first-target);
  long long g2=abs(g.card[0].second-target);
  long long g3=abs(g.card[0].first-g.card[0].second);
  return -max(g1,g2);
}

#define BSIZE 10000

using pdi=pair<double,int>;

int main(){
  start_clock();

  int n;
  cin >> n;
  Game inig;
  inig.card.resize(n);
  for(auto &nx : inig.card){
    cin >> nx.first >> nx.second;
  }
  inig.hand.clear();

  vector<Game> gs={inig};
  long long rr=-8e18;
  Game res=inig;

  for(int tr=0;tr<50;tr++){
    vector<Game> ng;
    priority_queue<pl,vector<pl>,greater<pl>> pq;
    for(auto &nx : gs){
      for(int i=0;i<n;i++){
        if(i!=0){break;}
        for(int j=i+1;j<n;j++){
          pl ci=nx.card[i];
          pl cj=nx.card[j];
          pl ck=f(ci,cj);

          nx.card[i]=ck;
          nx.card[j]=ck;
          nx.hand.push_back((i<<6)+j);

          long long ce=eval(nx);
          if(rr<ce){
            rr=ce;
            res=nx;
          }
          if(ng.size()<BSIZE){
            pq.push({ce,ng.size()});
            ng.push_back(nx);
          }
          else if(pq.top().first < ce){
            pdi od=pq.top();pq.pop();
            od.first=ce;
            pq.push(od);
            ng[od.second]=nx;
          }

          nx.card[i]=ci;
          nx.card[j]=cj;
          nx.hand.pop_back();
        }
      }
    }
    gs=ng;
  }

  cout << res.hand.size() << "\n";
  for(auto &nx : res.hand){
    cout << (nx/64)+1 << " " << (nx%64)+1 << "\n";
  }
  //for(auto &nx : res.card){
  // cout << nx.first << " " << nx.second << "\n";
  //}
  return 0;
}