#include <bits/stdc++.h>
#include <atcoder/all>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=b-1;i>=a;i--)
#define all(x) (x).begin(),(x).end()
#define pb(x) push_back(x);
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
typedef long long ll;
typedef long double lld;
using namespace std;
using namespace atcoder;

const double TIME_LIMIT = 0.92;
const ll BASE = 500000000000000000;

clock_t start=clock();
clock_t process=clock();
// random_device seed_gen;
// mt19937 engine(seed_gen());
mt19937 engine(0);
typedef pair<ll,ll> P;

const int N = 45;
const int M = 50;
ll A[N],B[N];

void Input(){
    int _n;cin >> _n;
    rep(i,0,N)cin >> A[i] >> B[i];
}

struct Solution{
    int X=0;
    vector<int> u,v;
    
    P Simulate(){
        ll a[N],b[N];rep(i,0,N)a[i]=A[i],b[i]=B[i];
        rep(i,0,X){
            ll tmp1=(a[u[i]]+a[v[i]])/2;
            ll tmp2=(b[u[i]]+b[v[i]])/2;
            a[u[i]]=tmp1;a[v[i]]=tmp1;
            b[u[i]]=tmp2;b[v[i]]=tmp2;
        }
        return P(a[0],b[0]);
    }

    void Output(){
        cout << X << endl;
        rep(i,0,X)cout << u[i]+1 << " " << v[i]+1 << endl;
    }
};

Solution InitSolve(){
    Solution res_sol;
    set<int> st;
    st.insert(0);
    rep(i,0,M){
        int x=random()%N;
        int y=random()%N;
        while(true){
            if(x!=y&&(st.count(x)||st.count(y))){
                break;
            }
            x=random()%N;
            y=random()%N;
        }
        res_sol.u.pb(x);
        res_sol.v.pb(y);
        res_sol.X++;
        st.insert(x);
        st.insert(y);
    }
    reverse(all(res_sol.u));
    reverse(all(res_sol.v));
    return res_sol;
}

tuple<int,int,int,ll,ll> Suggest(Solution &sol){
    int idx=random()%M;
    int x=random()%N;
    int y=random()%N;
    while(true){
        bool break_flag=true;
        if(x!=y){
            break_flag=false;
            rep(nidx,idx+1,M){
                if(sol.u[nidx]==x||sol.v[nidx]==x){
                    break_flag=true;
                    break;
                }
                if(sol.u[nidx]==y||sol.v[nidx]==y){
                    break_flag=true;
                    break;
                }
            }
        }
        else{
            break_flag=false;
        }
        if(break_flag){
            break;
        }
        idx=random()%M;
        x=random()%N;
        y=random()%N;
    }
    int pre_x=sol.u[idx];   
    int pre_y=sol.v[idx];
    sol.u[idx]=x;
    sol.v[idx]=y;
    P score=sol.Simulate();
    ll v1=abs(BASE-score.first);
    ll v2=abs(BASE-score.second);
    sol.u[idx]=pre_x;
    sol.v[idx]=pre_y;
    return make_tuple(idx,x,y,v1,v2);
}

Solution HillClimbing(Solution sol){
    Solution now_sol=sol;
    P now_score=now_sol.Simulate();
    ll now_v1=abs(BASE-now_score.first);
    ll now_v2=abs(BASE-now_score.second);
    while((double)(clock()-start)/CLOCKS_PER_SEC<TIME_LIMIT){
        int idx,next_x,next_y;
        ll next_v1,next_v2;
        tie(idx,next_x,next_y,next_v1,next_v2)=Suggest(now_sol);
        if(max(now_v1,now_v2)>max(next_v1,next_v2)){
            now_v1=next_v1;
            now_v2=next_v2;
            now_sol.u[idx]=next_x;
            now_sol.v[idx]=next_y;
        }
    }
    return now_sol;
}

int main(void){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    Input();
    Solution sol=InitSolve();
    // P res=sol.Simulate();
    Solution next_sol=HillClimbing(sol);
    next_sol.Output();
}