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.io.*;
  import java.util.*;
  
  public class Main {
  
      static class DSU {
  
          private int[] parent;
          private int totalGroup;
  
          public DSU(int n) {
              parent = new int[n];
              totalGroup = n;
              for (int i = 0; i < n; i++) {
                  parent[i] = i;
              }
          }
  
          public boolean union(int a, int b) {
              if (findParent(a) == findParent(b)) {
                  return false;
              }
              totalGroup--;
              parent[findParent(a)] = findParent(b);
              return true;
          }
  
          public int findParent(int a) {
              if (parent[a] != a) {
                  parent[a] = findParent(parent[a]);
              }
              return parent[a];
          }
  
          public int getTotalGroup() {
              return totalGroup;
          }
      }
  
      public static void main(String[] args) throws Exception {
          solve();
          io.close();
      }
  
  
      private static void solve() {
          int n = io.nextInt();
          int m = io.nextInt();
          int d = io.nextInt();
  
          DSU dsu1 = new DSU(n);
          for (int i = 0; i < m; i++) {
              dsu1.union(io.nextInt() - 1, io.nextInt() - 1);
          }
  
          DSU dsu2 = new DSU(n);
          for (int i = 0; i < d; i++) {
              dsu2.union(io.nextInt() - 1, io.nextInt() - 1);
          }
  
          List<int[]> output = new ArrayList<>();
  
          for (int i = 0; i < n; i++) {
              for (int j = i + 1; j < n; j++) {
                  if (dsu1.findParent(i) != dsu1.findParent(j)
                          && dsu2.findParent(i) != dsu2.findParent(j)) {
                      dsu1.union(i, j);
                      dsu2.union(i, j);
                      output.add(new int[]{i, j});
                  }
              }
          }
  
          io.println(output.size());
          for (int[] o : output) {
              io.println((o[0] + 1) + " " + (o[1] + 1));
          }
  
      }
  
      static void sort(int[] a) {
          ArrayList<Integer> l = new ArrayList<>(a.length);
          for (int i : a) l.add(i);
          Collections.sort(l);
          for (int i = 0; i < a.length; i++) a[i] = l.get(i);
      }
  
      //-----------PrintWriter for faster output---------------------------------
      public static FastIO io = new FastIO();
  
      //-----------MyScanner class for faster input----------
      static class FastIO extends PrintWriter {
          private InputStream stream;
          private byte[] buf = new byte[1 << 16];
          private int curChar, numChars;
  
          // standard input
          public FastIO() {
              this(System.in, System.out);
          }
  
          public FastIO(InputStream i, OutputStream o) {
              super(o);
              stream = i;
          }
  
          // file input
          public FastIO(String i, String o) throws IOException {
              super(new FileWriter(o));
              stream = new FileInputStream(i);
          }
  
          // throws InputMismatchException() if previously detected end of file
          private int nextByte() {
              if (numChars == -1) throw new InputMismatchException();
              if (curChar >= numChars) {
                  curChar = 0;
                  try {
                      numChars = stream.read(buf);
                  } catch (IOException e) {
                      throw new InputMismatchException();
                  }
                  if (numChars == -1) return -1; // end of file
              }
              return buf[curChar++];
          }
  
          // to read in entire lines, replace c <= ' '
          // with a function that checks whether c is a line break
          public String next() {
              int c;
              do {
                  c = nextByte();
              } while (c <= ' ');
              StringBuilder res = new StringBuilder();
              do {
                  res.appendCodePoint(c);
                  c = nextByte();
              } while (c > ' ');
              return res.toString();
          }
  
          public String nextLine() {
              int c;
              do {
                  c = nextByte();
              } while (c < '\n');
              StringBuilder res = new StringBuilder();
              do {
                  res.appendCodePoint(c);
                  c = nextByte();
              } while (c > '\n');
              return res.toString();
          }
  
          public int nextInt() { // nextLong() would be implemented similarly
              int c;
              do {
                  c = nextByte();
              } while (c <= ' ');
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = nextByte();
              }
              int res = 0;
              do {
                  if (c < '0' || c > '9')
                      throw new InputMismatchException();
                  res = 10 * res + c - '0';
                  c = nextByte();
              } while (c > ' ');
              return res * sgn;
          }
  
          public long nextLong() { // nextLong() would be implemented similarly
              int c;
              do {
                  c = nextByte();
              } while (c <= ' ');
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = nextByte();
              }
              long res = 0;
              do {
                  if (c < '0' || c > '9')
                      throw new InputMismatchException();
                  res = 10 * res + c - '0';
                  c = nextByte();
              } while (c > ' ');
              return res * sgn;
          }
  
          public double nextDouble() {
              return Double.parseDouble(next());
          }
      }
  //--------------------------------------------------------
  }