description: This is the easy version of the problem. The only difference between the two versions is the constraint on n. You can make hacks only if all versions of the problem are solved.
  
  A forest is an undirected graph without cycles (not necessarily connected).
  
  Mocha and Diana are friends in Zhijiang, both of them have a forest with nodes numbered from 1 to n, and they would like to add edges to their forests such that: 
  
    * After adding edges, both of their graphs are still forests. 
    * They add the same edges. That is, if an edge (u, v) is added to Mocha's forest, then an edge (u, v) is added to Diana's forest, and vice versa. 
  
  
  
  Mocha and Diana want to know the maximum number of edges they can add, and which edges to add.
  
  Input
  
  The first line contains three integers n, m_1 and m_2 (1 ≤ n ≤ 1000, 0 ≤ m_1, m_2 < n) — the number of nodes and the number of initial edges in Mocha's forest and Diana's forest.
  
  Each of the next m_1 lines contains two integers u and v (1 ≤ u, v ≤ n, u ≠ v) — the edges in Mocha's forest.
  
  Each of the next m_2 lines contains two integers u and v (1 ≤ u, v ≤ n, u ≠ v) — the edges in Diana's forest.
  
  Output
  
  The first line contains only one integer h, the maximum number of edges Mocha and Diana can add (in each forest).
  
  Each of the next h lines contains two integers u and v (1 ≤ u, v ≤ n, u ≠ v) — the edge you add each time.
  
  If there are multiple correct answers, you can print any one of them.
  
  Examples
  
  Input
  
  
  3 2 2
  1 2
  2 3
  1 2
  1 3
  
  
  Output
  
  
  0
  
  
  Input
  
  
  5 3 2
  5 4
  2 1
  4 3
  4 3
  1 4
  
  
  Output
  
  
  1
  2 4
  
  
  Input
  
  
  8 1 2
  1 7
  2 6
  1 5
  
  
  Output
  
  
  5
  5 2
  2 3
  3 4
  4 7
  6 8
  
  Note
  
  In the first example, we cannot add any edge.
  
  In the second example, the initial forests are as follows.
  
  <image>
  
  We can add an edge (2, 4).
  
  <image>
solution: import java.util.*;
  
  import java.io.*;
  
  public class cf {
      static Reader sc = new Reader();
      static PrintWriter out = new PrintWriter(System.out);
      static long mod = (long) 1e9 + 7;
  
      public static void main(String[] args) {
          int tc = 1;
          while (tc-- > 0) {
              int n = sc.ni(), m1 = sc.ni(), m2 = sc.ni();
              dsu d1 = new dsu(n);
              dsu d2 = new dsu(n);
              for (int i = 0; i < m1; i++) {
                  int u = sc.ni() - 1, v = sc.ni() - 1;
                  d1.union_set(u, v);
              }
              for (int i = 0; i < m2; i++) {
                  int u = sc.ni() - 1, v = sc.ni() - 1;
                  d2.union_set(u, v);
              }
              ArrayList<int[]> res = new ArrayList<>();
              for (int i = 0; i < n; i++) {
                  for (int j = i; j < n; j++) {
                      if (d1.find_set(i) != d1.find_set(j) && d2.find_set(i) != d2.find_set(j)) {
                          d1.union_set(i, j);
                          d2.union_set(i, j);
                          res.add(new int[] { i + 1, j + 1 });
                      }
                  }
              }
  
              out.println(res.size());
              for (int[] e : res)
                  out.println(e[0] + " " + e[1]);
  
          }
          out.close();
  
      }
  
      static class dsu {
          int[] par, rank;
  
          dsu(int n) {
              par = new int[n];
              rank = new int[n];
              for (int i = 0; i < n; i++) {
                  par[i] = i;
              }
          }
  
          // dsu with rank(depth)
          int find_set(int x) {
              if (par[x] == x)
                  return x;
              return par[x] = find_set(par[x]);
          }
  
          void union_set(int x, int y) {
              x = find_set(x);
              y = find_set(y);
              if (x == y)
                  return;
              if (rank[x] < rank[y]) {
                  int t = x;
                  x = y;
                  y = t;
              }
              par[y] = x;
              if (rank[x] == rank[y])
                  rank[x]++;
          }
      }
  
      public static long pow(long a, long b, long m) {
          if (b == 0) {
              return 1;
          }
          if (b % 2 == 0) {
              return pow((a * a) % m, b / 2, m) % m;
          } else {
              return (a * pow((a * a) % m, b / 2, m)) % m;
          }
      }
  
      // snippets
  
      static class Pair implements Comparable<Pair> {
          int x;
          int y;
  
          Pair(int x, int y) {
              this.x = x;
              this.y = y;
  
          }
  
          @Override
          public int compareTo(Pair o) {
              if (this.x > o.x)
                  return 1;
              else if (this.x < o.x)
                  return -1;
              else {
                  if (this.y > o.y)
                      return 1;
                  else if (this.y < o.y)
                      return -1;
                  else
                      return 0;
              }
          }
  
          public int hashCode() {
              int ans = 1;
              ans = x * 31 + y * 13;
              return ans;
          }
  
          @Override
          public boolean equals(Object o) {
              if (this == o) {
                  return true;
              }
              if (o == null) {
                  return false;
              }
              if (this.getClass() != o.getClass()) {
                  return false;
              }
              Pair other = (Pair) o;
              if (this.x == other.x && this.y == other.y) {
                  return true;
              }
              return false;
          }
  
      }
  
      static void add_map(HashMap<Integer, Integer> map, int v) {
          if (!map.containsKey(v)) {
              map.put(v, 1);
          } else {
              map.put(v, map.get(v) + 1);
          }
      }
  
      static void remove_map(HashMap<Integer, Integer> map, int v) {
          if (map.containsKey(v)) {
              map.put(v, map.get(v) - 1);
              if (map.get(v) == 0)
                  map.remove(v);
          }
      }
  
      static int gcd(int a, int b) {
          if (b == 0)
              return a;
          return gcd(b, a % b);
      }
  
      static long gcd(long a, long b) {
          if (b == 0)
              return a;
          return gcd(b, a % b);
      }
  
      static void sort(int[] arr) {
          // shuffle
          Random rand = new Random();
          for (int i = 0; i < arr.length; i++) {
              int j = rand.nextInt(i + 1);
              int tmp = arr[i];
              arr[i] = arr[j];
              arr[j] = tmp;
          }
          Arrays.sort(arr);
      }
  
      static void sort(long[] arr) {
          // shuffle
          Random rand = new Random();
          for (int i = 0; i < arr.length; i++) {
              int j = rand.nextInt(i + 1);
              long tmp = arr[i];
              arr[i] = arr[j];
              arr[j] = tmp;
          }
          Arrays.sort(arr);
      }
  
      static boolean isPrime(int n) {
          if (n <= 1)
              return false;
          if (n <= 3)
              return true;
          if (n % 2 == 0 || n % 3 == 0)
              return false;
          double sq = Math.sqrt(n);
  
          for (int i = 5; i <= sq; i = i + 6)
              if (n % i == 0 || n % (i + 2) == 0)
                  return false;
          return true;
      }
  
      static boolean isPrime(long n) {
          if (n <= 1)
              return false;
          if (n <= 3)
              return true;
          if (n % 2 == 0 || n % 3 == 0)
              return false;
          double sq = Math.sqrt(n);
  
          for (int i = 5; i <= sq; i = i + 6)
              if (n % i == 0 || n % (i + 2) == 0)
                  return false;
          return true;
      }
  
      static void print_arr(int A[]) {
          for (int i : A) {
              System.out.print(i + " ");
          }
          System.out.println();
      }
  
      static void print_arr(long A[]) {
          for (long i : A) {
              System.out.print(i + " ");
          }
          System.out.println();
      }
  
      static void print_arr(char A[]) {
          for (char i : A) {
              System.out.print(i + " ");
          }
          System.out.println();
      }
  
      static int min(int a, int b) {
          return Math.min(a, b);
      }
  
      static int min(int a, int b, int c) {
          return Math.min(a, Math.min(b, c));
      }
  
      static int min(int a, int b, int c, int d) {
          return Math.min(a, Math.min(b, Math.min(c, d)));
      }
  
      static int max(int a, int b) {
          return Math.max(a, b);
      }
  
      static int max(int a, int b, int c) {
          return Math.max(a, Math.max(b, c));
      }
  
      static int max(int a, int b, int c, int d) {
          return Math.max(a, Math.max(b, Math.max(c, d)));
      }
  
      static long min(long a, long b) {
          return Math.min(a, b);
      }
  
      static long min(long a, long b, long c) {
          return Math.min(a, Math.min(b, c));
      }
  
      static long min(long a, long b, long c, long d) {
          return Math.min(a, Math.min(b, Math.min(c, d)));
      }
  
      static long max(long a, long b) {
          return Math.max(a, b);
      }
  
      static long max(long a, long b, long c) {
          return Math.max(a, Math.max(b, c));
      }
  
      static long max(long a, long b, long c, long d) {
          return Math.max(a, Math.max(b, Math.max(c, d)));
      }
  
      static int max(int A[]) {
          int max = Integer.MIN_VALUE;
          for (int i = 0; i < A.length; i++) {
              max = Math.max(max, A[i]);
          }
          return max;
      }
  
      static int min(int A[]) {
          int min = Integer.MAX_VALUE;
          for (int i = 0; i < A.length; i++) {
              min = Math.min(min, A[i]);
          }
          return min;
      }
  
      static long max(long A[]) {
          long max = Long.MIN_VALUE;
          for (int i = 0; i < A.length; i++) {
              max = Math.max(max, A[i]);
          }
          return max;
      }
  
      static long min(long A[]) {
          long min = Long.MAX_VALUE;
          for (int i = 0; i < A.length; i++) {
              min = Math.min(min, A[i]);
          }
          return min;
      }
  
      static long sum(int A[]) {
          long sum = 0;
          for (int i : A) {
              sum += i;
          }
          return sum;
      }
  
      static long sum(long A[]) {
          long sum = 0;
          for (long i : A) {
              sum += i;
          }
          return sum;
      }
  
      static ArrayList<Integer> sieve(int n) {
          ArrayList<Integer> primes = new ArrayList<>();
          boolean[] isPrime = new boolean[n];
          Arrays.fill(isPrime, true);
          isPrime[0] = isPrime[1] = false;
          for (int i = 2; i * i <= n; i++) {
              if (isPrime[i]) {
                  for (int j = i * i; j < n; j += i) {
                      isPrime[j] = false;
                  }
              }
          }
          for (int i = 2; i < n; i++) {
              if (isPrime[i])
                  primes.add(i);
          }
          return primes;
      }
  
      static class Reader {
          BufferedReader br;
          StringTokenizer st;
  
          Reader() {
              br = new BufferedReader(new InputStreamReader(System.in));
              st = new StringTokenizer("");
          }
  
          Reader(File f) throws FileNotFoundException {
              br = new BufferedReader(new FileReader(f));
              st = new StringTokenizer("");
          }
  
          String next() {
              while (!st.hasMoreTokens())
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                  }
              return st.nextToken();
          }
  
          int ni() {
              return Integer.parseInt(next());
          }
  
          long nl() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          int[] nai(int n) {
              int[] a = new int[n];
              for (int i = 0; i < n; i++)
                  a[i] = ni();
              return a;
          }
  
          long[] nal(int n) {
              long[] a = new long[n];
              for (int i = 0; i < n; i++)
                  a[i] = nl();
              return a;
          }
      }
  
  }