#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<(b);++i)
using namespace std;
using pii = pair<int,int>;
using ll = long long;
using pll = pair<ll,ll>;
using vi = vector<int>;
 
using ld = long double;
 
#define all(x) (x).begin(), (x).end()
 
const int maxn = 1e6+10, inf = 1e9+100;
const ll linf = 1e18+100;
const int mod = 1e9+7;
 
const ld eps = 1e-9;
const ld PI = acos(-1.L);

int bit[maxn];
void upd(int a,int b){
  for(;a<maxn;a+=a&-a)bit[a]+=b;
}
int qu(int a){
  int b=0;
  for(;a;a-=a&-a)b+=bit[a];
  return b;
}

pii seg[maxn * 2];
int n;
pii qu(int l,int r) {
  pii ans = {inf,inf};
  l+=n,r+=n;
  while(l<=r){
    if(l&1)ans=min(ans,seg[l]),l++;
    if(!(r&1))ans=min(ans,seg[r]),r--;
    l>>=1;r>>=1;
  }
  return ans;
}

int a[maxn], b[maxn];
int v[maxn];

vector<pii> ans;

void rec(int l,int r){
  if(r<l)return;
  auto [v,ind] = qu(l,r);
  // cerr << l << " "  << r << " " << ind << endl;;
  ind *= -1;
  ans.push_back({l,v});
  rec(l,ind-1);
  rec(ind+1,r);
}

void solvee(){
  cin >> n;
  for(int i=0;i<=n;i++)bit[i]=a[i]=b[i]=v[i]=0;
  ans.clear();
  for(int i=0;i<=2*n;i++)seg[i]={0,0};
  for(int i = 0;i<n;i++){
    cin >> a[i] >> b[i];
  }
  for(int i=1;i<=n;i++)upd(i,1);
  for(int i=n-1;i>=0;i--){
    v[qu(a[i])] = b[i];
    upd(a[i],1);
  }
  for(int i=1;i<=n;i++){
    seg[n+i] = {v[i],-i};
  }
  for(int i=n;i>=1;i--){
    seg[i] = min(seg[2*i],seg[2*i+1]);
  }
  ans.clear();
  rec(1,n);
  for(auto [a,b] : ans) {
    cout << a << " " << b << "\n";
  }
}

void solve(){
  int tc;
  cin >> tc;
  while(tc--){
    solvee();
  }
}
 
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout<<fixed;
  cout.precision(20);
  solve();
}