source_code: import java.io.*;
  import java.util.*;
  
  public class Main {
  
      private static void solve(InputReader in, OutputWriter out) {
          int n = in.nextInt();
  
          List<List<Integer>> g = new ArrayList<>(n + 1);
          for (int i = 0; i < n + 1; i++) {
              g.add(new LinkedList<>());
          }
  
          int degree1 = 0, degree2 = 0, root = 0;
          for (int i = 0; i < n - 1; i++) {
              int a = in.nextInt();
              int b = in.nextInt();
  
              g.get(a).add(b);
              g.get(b).add(a);
  
              if (g.get(a).size() > degree1) {
  
                  if (a == root) {
                      degree1 = g.get(a).size();
                  } else {
                      degree2 = degree1;
                      degree1 = g.get(a).size();
                      root = a;
                  }
  
              } else if (g.get(a).size() > degree2) {
                  degree2 = g.get(a).size();
              }
  
              if (g.get(b).size() > degree1) {
  
                  if (b == root) {
                      degree1 = g.get(b).size();
                  } else {
                      degree2 = degree1;
                      degree1 = g.get(b).size();
                      root = b;
                  }
  
              } else if (g.get(b).size() > degree2) {
                  degree2 = g.get(b).size();
              }
          }
  
          if (degree2 > 2) {
              out.print("No");
          } else {
              out.println("Yes");
  
              List<Integer> leaves = new LinkedList<>();
              for (int i = 1; i <= n; i++) {
                  if (i != root) {
                      if (g.get(i).size() == 1) {
                          leaves.add(i);
                      }
                  }
              }
  
              out.println(leaves.size());
              for (int i : leaves) {
                  out.println(root + " " + i);
              }
          }
      }
  
      private static void shuffleArray(int[] array) {
          int index;
          Random random = new Random();
          for (int i = array.length - 1; i > 0; i--) {
              index = random.nextInt(i + 1);
              if (index != i) {
                  array[index] ^= array[i];
                  array[i] ^= array[index];
                  array[index] ^= array[i];
              }
          }
      }
  
      public static void main(String[] args) {
          InputReader in = new InputReader(System.in);
          OutputWriter out = new OutputWriter(System.out);
          solve(in, out);
          in.close();
          out.close();
      }
  
      private static class InputReader {
          private BufferedReader br;
          private StringTokenizer st;
  
          InputReader(InputStream is) {
              br = new BufferedReader(new InputStreamReader(is));
              st = null;
          }
  
          String nextLine() {
              String line = null;
              try {
                  line = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return line;
          }
  
          String next() {
              while (st == null || !st.hasMoreTokens()) {
                  String line = nextLine();
                  if (line == null) return null;
                  st = new StringTokenizer(line);
              }
              return st.nextToken();
          }
  
          byte nextByte() {
              return Byte.parseByte(next());
          }
  
          short nextShort() {
              return Short.parseShort(next());
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          void close() {
              try {
                  br.close();
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
      }
  
      private static class OutputWriter {
          BufferedWriter bw;
  
          OutputWriter(OutputStream os) {
              bw = new BufferedWriter(new OutputStreamWriter(os));
          }
  
          void print(int i) {
              print(Integer.toString(i));
          }
  
          void println(int i) {
              println(Integer.toString(i));
          }
  
          void print(long l) {
              print(Long.toString(l));
          }
  
          void println(long l) {
              println(Long.toString(l));
          }
  
          void print(double d) {
              print(Double.toString(d));
          }
  
          void println(double d) {
              println(Double.toString(d));
          }
  
          void print(boolean b) {
              print(Boolean.toString(b));
          }
  
          void println(boolean b) {
              println(Boolean.toString(b));
          }
  
          void print(char c) {
              try {
                  bw.write(c);
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
  
          void println(char c) {
              println(Character.toString(c));
          }
  
          void print(String s) {
              try {
                  bw.write(s);
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
  
          void println(String s) {
              print(s);
              print('\n');
          }
  
          void close() {
              try {
                  bw.close();
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
      }
  }
  