#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, U b) {
  if (a < b) a = b;
}
template <class T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T, class T1>
inline void gn(T &first, T1 &second) {
  gn(first);
  gn(second);
}
template <class T, class T1, class T2>
inline void gn(T &first, T1 &second, T2 &z) {
  gn(first);
  gn(second);
  gn(z);
}
template <class T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <class T>
inline void printsp(T first) {
  print(first);
  putchar(' ');
}
template <class T>
inline void println(T first) {
  print(first);
  putchar('\n');
}
template <class T, class U>
inline void print(T first, U second) {
  printsp(first);
  println(second);
}
template <class T, class U, class V>
inline void print(T first, U second, V z) {
  printsp(first);
  printsp(second);
  println(z);
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = 1LL * a * a * a % m)
    if (!b & 1) ans = 1LL * ans * a % m;
  return ans;
}
vector<int> cent;
vector<int> adj[222222];
int pa[222222];
int n;
vector<pair<pair<int, int>, int> > ans;
void answer(int first, int second, int z) {
  if (second == z) return;
  ans.push_back(pair<pair<int, int>, int>(pair<int, int>(first, second), z));
}
int find_Centorid(int u, int fa = 0) {
  int sz = 1, mx = 0;
  for (int i = 0; i < adj[u].size(); i++) {
    int v = adj[u][i];
    if (v == fa) continue;
    int sz_v = find_Centorid(v, u);
    smax(mx, sz_v);
    sz += sz_v;
  }
  if (mx * 2 <= n and sz * 2 >= n) cent.push_back(u);
  return sz;
}
void dfs(int u, int fa, vector<int> &dfn) {
  pa[u] = fa;
  for (int i = 0; i < adj[u].size(); i++) {
    int v = adj[u][i];
    if (v == fa) continue;
    dfs(v, u, dfn);
  }
  dfn.push_back(u);
}
void solve(int u, int fa = 0) {
  for (int i = 0; i < adj[u].size(); i++) {
    int v = adj[u][i];
    if (v == fa) continue;
    vector<int> dfn;
    dfs(v, u, dfn);
    answer(u, v, dfn[0]);
    for (int i = 0; i < dfn.size() - 1; i++)
      answer(dfn[i], pa[dfn[i]], dfn[i + 1]);
    for (int i = (int)dfn.size() - 3; i >= 0; i--)
      answer(dfn[i], dfn[i + 1], v);
    answer(u, dfn[0], v);
  }
}
int main() {
  int u, v;
  gn(n);
  for (int i = 1; i < n; i++) {
    gn(u, v);
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  find_Centorid(1);
  if (cent.size() == 1)
    solve(cent[0], 0);
  else
    solve(cent[0], cent[1]), solve(cent[1], cent[0]);
  println(ans.size());
  for (int i = 0; i < ans.size(); i++)
    print(ans[i].first.first, ans[i].first.second, ans[i].second);
}
