description: Lord Omkar would like to have a tree with n nodes (3 ≤ n ≤ 10^5) and has asked his disciples to construct the tree. However, Lord Omkar has created m (1 ≤ m < n) restrictions to ensure that the tree will be as heavenly as possible. 
  
  A tree with n nodes is an connected undirected graph with n nodes and n-1 edges. Note that for any two nodes, there is exactly one simple path between them, where a simple path is a path between two nodes that does not contain any node more than once.
  
  Here is an example of a tree: 
  
  <image>
  
  A restriction consists of 3 pairwise distinct integers, a, b, and c (1 ≤ a,b,c ≤ n). It signifies that node b cannot lie on the simple path between node a and node c. 
  
  Can you help Lord Omkar and become his most trusted disciple? You will need to find heavenly trees for multiple sets of restrictions. It can be shown that a heavenly tree will always exist for any set of restrictions under the given constraints.
  
  Input
  
  Each test contains multiple test cases. The first line contains the number of test cases t (1 ≤ t ≤ 10^4). Description of the test cases follows.
  
  The first line of each test case contains two integers, n and m (3 ≤ n ≤ 10^5, 1 ≤ m < n), representing the size of the tree and the number of restrictions.
  
  The i-th of the next m lines contains three integers a_i, b_i, c_i (1 ≤ a_i, b_i, c_i ≤ n, a, b, c are distinct), signifying that node b_i cannot lie on the simple path between nodes a_i and c_i. 
  
  It is guaranteed that the sum of n across all test cases will not exceed 10^5.
  
  Output
  
  For each test case, output n-1 lines representing the n-1 edges in the tree. On each line, output two integers u and v (1 ≤ u, v ≤ n, u ≠ v) signifying that there is an edge between nodes u and v. Given edges have to form a tree that satisfies Omkar's restrictions.
  
  Example
  
  Input
  
  
  2
  7 4
  1 2 3
  3 4 5
  5 6 7
  6 5 4
  5 3
  1 2 3
  2 3 4
  3 4 5
  
  
  Output
  
  
  1 2
  1 3
  3 5
  3 4
  2 7
  7 6
  5 1
  1 3
  3 2
  2 4
  
  Note
  
  The output of the first sample case corresponds to the following tree: 
  
  <image> For the first restriction, the simple path between 1 and 3 is 1, 3, which doesn't contain 2. The simple path between 3 and 5 is 3, 5, which doesn't contain 4. The simple path between 5 and 7 is 5, 3, 1, 2, 7, which doesn't contain 6. The simple path between 6 and 4 is 6, 7, 2, 1, 3, 4, which doesn't contain 5. Thus, this tree meets all of the restrictions.
  
  The output of the second sample case corresponds to the following tree: 
  
  <image>
solution: import java.io.BufferedReader;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.*;
  import java.util.concurrent.LinkedBlockingDeque;
  
  import javax.print.attribute.HashAttributeSet;
  import javax.swing.JLabel;
  
  import java.io.PrintStream;
  import java.sql.Blob;
          
      public class Solution {
  
          public static boolean Local(){
              try{ 
                  return System.getenv("LOCAL_SYS")!=null;
              }catch(Exception e){
                  return false;
              }
          }   
  
          public static boolean LOCAL;
  
          static class FastScanner {
  
                  BufferedReader br;
                  StringTokenizer st ;
  
                  FastScanner(){
                      br =  new BufferedReader(new InputStreamReader(System.in));
                      st = new StringTokenizer("");
                  }
  
                  FastScanner(String file) {
  
                      try{
                          br =  new BufferedReader(new InputStreamReader(new FileInputStream(file)));
                          st = new StringTokenizer("");
                      }catch(FileNotFoundException e) {
                          // TODO Auto-generated catch block
                          System.out.println("file not found");
                          e.printStackTrace();
                      }
                      
                  }
                  
  
                  String next() {
                      while (!st.hasMoreTokens())
                          try {
                              st = new StringTokenizer(br.readLine());
                          } catch (IOException e) {
                          }
                      return st.nextToken();
                  }
  
                  int nextInt() {
                      return Integer.parseInt(next());
                  }
  
                  long nextLong() {
                      return Long.parseLong(next());
                  }
                  String readLine() throws IOException{
                      return br.readLine();
                  }
              }
                                  
          static class Pair<T,X> {
  
              T first;
              X second;
              
              Pair(T first,X second){
                  this.first = first;
                  this.second = second;
              }
  
              @Override
              public int hashCode(){
                  return Objects.hash(first,second);
              }
  
              @Override
              public boolean equals(Object obj){
                  return obj.hashCode() == this.hashCode();
              }
  
          }
  
  
          static PrintStream debug = null;
  
          static class TreeNode{
              TreeNode left;
              TreeNode right;
              int l;
              int r;
              long gcd;
              TreeNode(int l,int r){
                  this.l = l;
                  this.r = r;
                  this.gcd = 0;
                  this.left = null;
                  this.right = null;
              }
          }
  
          static long mod = (long)(Math.pow(10,9) + 7); 
          
  
          public static void main(String[] args) throws Exception {
              
              FastScanner s = new FastScanner();
  
              LOCAL = Local();
  
              
              if(LOCAL){
                  s = new FastScanner("src/input.txt");
                  PrintStream o = new PrintStream("src/sampleout.txt");
                  debug = new PrintStream("src/debug.txt");
                  System.setOut(o);
              }
  
              long mod = 1000000007;
              
              int tcr = s.nextInt();     
          
              StringBuilder sb = new StringBuilder();
  
              int dx[] = {0,0,-1,1,1,-1,1,-1};
              int dy[] = {-1,1,0,0,1,1,-1,-1};
              
          
              for(int tc=0;tc<tcr;tc++){
                  int n = s.nextInt();
                  int res = s.nextInt();
                  int pos[] = new int[n];
                  for(int i=0;i<n;i++){pos[i] = i;}
                  int included = -1;
                  int cnt = 0;
                  int allowed[] = new int[n];
                  for(int i=0;i<res;i++){
                      int a = s.nextInt();
                      int b = s.nextInt();
                      int c = s.nextInt();
                      b--;
                      allowed[b] = 1;
                  }
                  int root = -1;
                  for(int i=0;i<n;i++){
                      if(allowed[i] == 0){
                          root = i;break;
                      }
                  }
                  for(int i=0;i<n;i++){
                      if(root == i){continue;}
                      sb.append((root+1)+" "+(i+1)+"\n");
                  }
  
                  
              }
              
              print(sb.toString());
          }
          public static boolean isPrime(int n){
              for(int i=2;(i*i)<=n;i++){
                  if((n%i) == 0){
                      return false;
                  }    
              }
              return true;
          }
  
          public static TreeNode buildTree(int l,int r,List<Long> arr){
              
              if(l>r){return null;}
           //   println(l+" "+r);
              if(l == r){
                  TreeNode ans = new TreeNode(l,r);
                  ans.gcd = arr.get(l);
                  return ans;
              }
  
              TreeNode curr = new TreeNode(l,r);
              
              int mid = (l + r)/2;
              
              curr.left =  buildTree(l, mid, arr);
              
              curr.right = buildTree(mid+1,r, arr);
              
              long gcd = 0;
              
              if(curr.left != null){
                  gcd = gcd(gcd,curr.left.gcd);
              }
              
              if(curr.right != null){
                  gcd = gcd(gcd,curr.right.gcd);
              }
              curr.gcd = gcd;
              return curr;
          }
  
          public static long query(TreeNode node,int l,int r){
              
              if(l > r){
                  return 0;
              }
  
           //   println(l+" "+r+" "+node);
  
              // if(node == null){
              //     return 0;
              // }
  
              if(node.l == l && node.r == r){
                  return node.gcd;
              }
  
              int mid = (node.l + node.r)/2;
  
              int ls = l;
              int le = Math.min(r,mid);
              int rs = Math.max(l,mid+1);
              int re = r;
  
              return gcd(query(node.left,ls,le),query(node.right,rs,re));
          }
  
          
          static long getPairsCount(int n, long sum,long arr[])
          {
              HashMap<Long, Integer> hm = new HashMap<>();
          
          
              for (int i = 0; i < n; i++) {
                  
                  if (!hm.containsKey(arr[i])){
                      hm.put(arr[i], 0);
                      }
          
                  hm.put(arr[i], hm.get(arr[i]) + 1);
              }
              long twice_count = 0;
              for (int i = 0; i < n; i++) {
                  if (hm.get(sum - arr[i]) != null){
                      twice_count += hm.get(sum - arr[i]);
                  }
          
                  
                  if (sum - arr[i] == arr[i]){
                      twice_count--;
                  }
              }
          
              // return the half of twice_count
              return twice_count / 2l;
          }
          public static long ncr(int n,int r,long fact[]){
              if(r==0){return 1l;}
              long ans = fact[n];
              long denom = mulmod(fact[r], fact[n-r], mod);
              ans = mulmod(ans,modpow(denom,mod-2, mod),mod);
              return ans;
          }
  
          public static List<long[]> prime_factors(long n){
  
              List<long[]> list = new ArrayList<>();
              
              for(long i=2;i<=(Math.sqrt(n));i++){
  
                  if(n % i == 0){
                      
                      int cnt = 0;
                      
                      while( (n % i) == 0){
                          n = n/i;
                          cnt++;
                          
                      }
  
                      list.add(new long[]{i,cnt});
                  }
              }
  
  
              if(n!=1){
                  list.add(new long[]{n,1l});
              }
  
              return list;
  
          }
  
          public static boolean check(int arr[]){
              for(int i=1;i<arr.length;i++){
                  if(arr[i] < arr[i-1]){
                      return false;
                  }
              }
              return true;
          }
  
  
          public static boolean inRange(int r1,int r2,int val){
              return ((val >= r1) && (val <= r2));
          }
  
          static int len(long num){
              return Long.toString(num).length();
          }
  
          static long mulmod(long a, long b,long mod)
          {
              long ans = 0l;
              
              while(b > 0l){
                  long curr = (b & 1l);
                  if(curr == 1l){
                      ans = ((ans % mod) + a) % mod;
                  }
                  
                  a = (a + a) % mod;
  
                  b = b >> 1;
              }
  
              return ans;
          }
  
  
          public static void dbg(PrintStream ps,Object... o) throws Exception{
              if(ps == null){
                  return;
              }
              Debug.dbg(ps,o);
          }
  
          public static long modpow(long num,long pow,long mod){
  
              long val = num;
              long ans = 1l;
  
              while(pow > 0l){
                  
                  long bit = pow & 1l;
  
                  if(bit == 1){
                      ans = (ans * (val%mod))%mod;
                  }
  
                  val = (val * val) % mod;
                  pow = pow >> 1;
              }
  
              return ans;
  
          }
  
          public static char get(int n){
              return (char)('a' + n);
          }
  
          public static long[] sort(long arr[]){
              List<Long> list = new ArrayList<>();
              for(long n : arr){list.add(n);}
              Collections.sort(list);
              for(int i=0;i<arr.length;i++){
                  arr[i] = list.get(i);
              }
              return arr;
          }
  
          public static int[] sort(int arr[]){
              List<Integer> list = new ArrayList<>();
              for(int n : arr){list.add(n);}
              Collections.sort(list);
              for(int i=0;i<arr.length;i++){
                  arr[i] = list.get(i);
              }
              return arr;
          }
  
          // return the (index + 1)
          // where index is the pos of just smaller element
          // i.e count of elemets strictly less than num
          public static int justSmaller(long arr[],long num){
              //  System.out.println(num+"@");
              int st = 0;
              int e = arr.length - 1;
  
              int ans = -1;
  
              while(st <= e){
  
                  int mid = (st + e)/2;
  
                  if(arr[mid] >= num){
                      e = mid - 1;
                  }else{
                      ans = mid;
                      st = mid + 1;
                  }
  
              }
  
  
              return ans + 1;
  
          }
          public static int justSmaller(int arr[],int num){
              //  System.out.println(num+"@");
              int st = 0;
              int e = arr.length - 1;
  
              int ans = -1;
  
              while(st <= e){
  
                  int mid = (st + e)/2;
  
                  if(arr[mid] >= num){
                      e = mid - 1;
                  }else{
                      ans = mid;
                      st = mid + 1;
                  }
  
              }
  
  
              return ans + 1;
  
          }
          
          //return (index of just greater element)
          //count of elements smaller than or equal to num
  
          public static int justGreater(long arr[],long num){
              int st = 0;
              int e = arr.length - 1;
  
              int ans = arr.length;
  
              while(st <= e){
                  
                  int mid = (st + e)/2;
  
                  if(arr[mid] <= num){
                      st = mid + 1;
                  }else{
                      ans = mid;
                      e = mid - 1;
                  }
              }
  
              return ans;
  
          }
  
          public static int justGreater(int arr[],int num){
              int st = 0;
              int e = arr.length - 1;
  
              int ans = arr.length;
  
              while(st <= e){
                  
                  int mid = (st + e)/2;
  
                  if(arr[mid] <= num){
                      st = mid + 1;
                  }else{
                      ans = mid;
                      e = mid - 1;
                  }
              }
  
              return ans;
  
          }
  
          
  
          public static void println(Object obj){
              System.out.println(obj.toString());
          }
  
          public static void print(Object obj){
              System.out.print(obj.toString());
          }
  
          public static int gcd(int a,int b){
              if(b == 0){return a;}
              return gcd(b,a%b);
          }
  
          public static long gcd(long a,long b){
              if(b == 0l){
                  return a;
              }
  
              return gcd(b,a%b);
          }
  
          public static int find(int parent[],int v){
              if(parent[v] == v){
                  return v;
              }
              
              return parent[v] = find(parent, parent[v]);
          }
  
  
  
          public static List<Integer> sieve(){
          
                  List<Integer> prime = new ArrayList<>();
  
                  int arr[] = new int[300001];
  
              Arrays.fill(arr,1);
  
              arr[1] = 0;
              arr[2] = 1;
  
              for(int i=2;i<300001;i++){
                  
                  if(arr[i] == 1){
                      
                      prime.add(i);
  
                      for(long j = (i*1l*i);j<300001;j+=i){
                          arr[(int)j] = 0;
                      }
                  }
              }
  
              return prime;
          }
  
          static boolean isPower(long n,long a){
              
              long log = (long)(Math.log(n)/Math.log(a));
  
              long power = (long)Math.pow(a,log);
  
              if(power == n){return true;}
  
              return false;
          }
  
  
          private static int mergeAndCount(int[] arr, int l,int m, int r)
          {
  
              // Left subarray
              int[] left =  Arrays.copyOfRange(arr, l, m + 1);
  
              // Right subarray
              int[] right = Arrays.copyOfRange(arr, m + 1, r + 1);
  
              int i = 0, j = 0, k = l, swaps = 0;
  
              while (i < left.length && j < right.length) {
                  if (left[i] <= right[j])
                      arr[k++] = left[i++];
                  else {
                      arr[k++] = right[j++];
                      swaps += (m + 1) - (l + i);
                  }
              }
              while (i < left.length)
                  arr[k++] = left[i++];
              while (j < right.length)
                  arr[k++] = right[j++];
              return swaps;
          }
  
          // Merge sort function
          private static int mergeSortAndCount(int[] arr, int l,int r)
          {
  
              // Keeps track of the inversion count at a
              // particular node of the recursion tree
              int count = 0;
  
              if (l < r) {
                  int m = (l + r) / 2;
  
                  // Total inversion count = left subarray count
                  // + right subarray count + merge count
  
                  // Left subarray count
                  count += mergeSortAndCount(arr, l, m);
  
                  // Right subarray count
                  count += mergeSortAndCount(arr, m + 1, r);
  
                  // Merge count
                  count += mergeAndCount(arr, l, m, r);
              }
  
              return count;
          }
  
          static class Debug{
              //change to System.getProperty("ONLINE_JUDGE")==null; for CodeForces
              public static final boolean LOCAL = System.getProperty("ONLINE_JUDGE")==null;
  
              
  
              private static <T> String ts(T t) {
                  if(t==null) {
                      return "null";
                  }
                  try {
                      return ts((Iterable) t);
                  }catch(ClassCastException e) {
                      if(t instanceof int[]) {
                          String s = Arrays.toString((int[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }else if(t instanceof long[]) {
                          String s = Arrays.toString((long[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }else if(t instanceof char[]) {
                          String s = Arrays.toString((char[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }else if(t instanceof double[]) {
                          String s = Arrays.toString((double[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }else if(t instanceof boolean[]) {
                          String s = Arrays.toString((boolean[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }
                      try {
                          return ts((Object[]) t);
                      }catch(ClassCastException e1) {
                          return t.toString();
                      }
                  }
              }
              private static <T> String ts(T[] arr) {
                  StringBuilder ret = new StringBuilder();
                  ret.append("{");
                  boolean first = true;
                  for(T t: arr) {
                      if(!first) {
                          ret.append(", ");
                      }
                      first = false;
                      ret.append(ts(t));
                  }
                  ret.append("}");
                  return ret.toString();
              }
              private static <T> String ts(Iterable<T> iter) {
                  StringBuilder ret = new StringBuilder();
                  ret.append("{");
                  boolean first = true;
                  for(T t: iter) {
                      if(!first) {
                          ret.append(", ");
                      }
                      first = false;
                      ret.append(ts(t));
                  }
                  ret.append("}");
                  return ret.toString();
              }
              public static void dbg(PrintStream ps,Object... o) throws Exception {
                  if(LOCAL) {
                      System.setErr(ps);
                      System.err.print("Line #"+Thread.currentThread().getStackTrace()[2].getLineNumber()+": [");
                      for(int i = 0; i<o.length; i++) {
                          if(i!=0) {
                              System.err.print(", ");
                          }
                          System.err.print(ts(o[i]));
                      }
                      System.err.println("]");
                  }
              }
      }
  
      }
  
  
      