#include<bits/stdc++.h>
#include "wheretoreach.h"
using namespace std;
#define vec vector
#define pb push_back
#define eb emplace_back
#define siz(vec) ((int)(vec).size())
#define all(vec) (vec).begin(),(vec).end()
template<class T>
void operator +=(vec<T> &a,T b){a.push_back(b);}
template<class T>
void operator --(vec<T> &a){a.pop_back();}
#define pii pair<int,int>
#define x first
#define y second
#define mp make_pair
#define exc(exp) if(exp)continue;
#define stop(exp) if(exp)break;
#define ret(exp) if(exp)return;
#define deb(var) cerr<<#var<<'='<<(var)<<"; "
#define debl(var) cerr<<#var<<'='<<(var)<<";\n"
#define ins insert
#define era erase
#define lb lower_bound
#define inf (long long)(1e9)
template<class T>
bool Min(T &x,T y){return x>y?x=y,1:0;}
template<class T>
bool Max(T &x,T y){return x<y?x=y,1:0;}

int add(int x);
int remove(int x);
void report(int x,int y);

int n,vis[10010],tmp[10010],ins[10010];
void sol(int l,int r,vec<int> w){
    ret(l>r);
    int mid=(l+r)>>1;

    vec<int> v;
    if(l==1&&r==n){
        v=w;
    }else{
        for(auto x:w)tmp[x]=0;
        fill(vis+l,vis+r+1,0);
        for(int T=1;;T++){
            for(int i=l;i<=r;i++){
                int x=add(i);
                if(x>1)tmp[i]=1;
                if(x>1||vis[i]){
                    remove(i);
                }else{
                    ins[i]=1;
                    vis[i]=1;
                }
            }
            for(auto x:w){
                exc(tmp[x]);
                if(x<=l){
                }else if(x<=r){

                }else{
                    if(add(x)>1)tmp[x]=1;
                    assert(remove(x)<=1);
                }
            }
            for(int i=l;i<=r;i++){
                if(ins[i]){
                    remove(i);
                    ins[i]=0;
                }
            }
            if(count(vis+l,vis+r+1)==r-l+1)break;
        }
        for(auto x:w){
            if(tmp[x])v+=x;
        }
    }

    w=v;
    if(l==r){
        for(auto x:w){
            report(l,x);
        }
    }else{
        sol(l,mid,w);
        sol(mid+1,r,w);
    }
}
void solve(int N){
    n=N;
    vec<int> v(n-1);
    iota(all(v),2);
    sol(1,n,v);
}

implementer.cpp: In function ‘void Interactor::init()’:
implementer.cpp:25:22: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   25 |                 scanf("%d",&n);
      |                 ~~~~~^~~~~~~~~
implementer.cpp:30:30: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   30 |                         scanf("%d%d",&x,&y); v[x].push_back(y),v[y].push_back(x);
      |                         ~~~~~^~~~~~~~~~~~~~
answer.code: In function ‘void sol(int, int, std::vector<int>)’:
answer.code:73:21: error: no matching function for call to ‘count(int*, int*)’
   73 |             if(count(vis+l,vis+r+1)==r-l+1)break;
      |                ~~~~~^~~~~~~~~~~~~~~
In file included from /usr/include/c++/13/algorithm:61,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:51,
                 from answer.code:1:
/usr/include/c++/13/bits/stl_algo.h:4072:5: note: candidate: ‘template<class _IIter, class _Tp> constexpr typename std::iterator_traits< <template-parameter-1-1> >::difference_type std::count(_IIter, _IIter, const _Tp&)’
 4072 |     count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
      |     ^~~~~
/usr/include/c++/13/bits/stl_algo.h:4072:5: note:   template argument deduction/substitution failed:
answer.code:73:21: note:   candidate expects 3 arguments, 2 provided
   73 |             if(count(vis+l,vis+r+1)==r-l+1)break;
      |                ~~~~~^~~~~~~~~~~~~~~
In file included from /usr/include/c++/13/algorithm:73:
/usr/include/c++/13/pstl/glue_algorithm_defs.h:101:1: note: candidate: ‘template<class _ExecutionPolicy, class _ForwardIterator, class _Tp> __pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, typename std::iterator_traits<_II>::difference_type> std::count(_ExecutionPolicy&&, _ForwardIterator, _ForwardIterator, const _Tp&)’
  101 | count(_ExecutionPolicy&& __exec, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value);
      | ^~~~~
/usr/include/c++/13/pstl/glue_algorithm_defs.h:101:1: note:   template argument deduction/substitution failed:
answer.code:73:21: note:   candidate expects 4 arguments, 2 provided
   73 |             if(count(vis+l,vis+r+1)==r-l+1)break;
      |                ~~~~~^~~~~~~~~~~~~~~