#include <bits/stdc++.h>
using namespace std;
const int N = 200010;
struct Edge {
  int v, next;
  Edge(int v = 0, int next = 0) : v(v), next(next) {}
} e[N << 1];
int n, degree[N] = {0};
int id = 0, head[N] = {0};
long long ans = 0;
int st[2], d[2][N] = {0};
inline void addedge(int u, int v) {
  e[++id].v = v;
  e[id].next = head[u];
  head[u] = id;
}
int bfs(int ST, int dis[]) {
  bool vis[N] = {0};
  queue<int> que;
  dis[ST] = 0;
  vis[ST] = true;
  que.push(ST);
  int res = ST;
  while (!que.empty()) {
    int u = que.front();
    que.pop();
    for (int i = head[u]; i; i = e[i].next) {
      int v = e[i].v;
      if (vis[v]) continue;
      res = v;
      vis[v] = true;
      dis[v] = dis[u] + 1;
      que.push(v);
    }
  }
  return res;
}
vector<pair<pair<int, int>, int> > ve;
void update(int u, queue<int>& que) {
  for (int i = head[u]; i; i = e[i].next) {
    int v = e[i].v;
    --degree[v];
    if (degree[v] == 1) que.push(v);
  }
}
void cut() {
  int len = d[0][st[1]];
  queue<int> que;
  for (int i = 1; i <= n; ++i) {
    if (d[0][i] + d[1][i] == len)
      continue;
    else if (degree[i] == 1)
      que.push(i);
  }
  while (!que.empty()) {
    int v = que.front();
    que.pop();
    update(v, que);
    if (d[0][v] > d[1][v]) {
      ans += d[0][v];
      ve.push_back(make_pair(make_pair(v, st[0]), v));
    } else {
      ans += d[1][v];
      ve.push_back(make_pair(make_pair(v, st[1]), v));
    }
  }
}
void dem() {
  int len = d[0][st[1]];
  queue<int> que;
  que.push(st[0]);
  vector<int> de;
  while (!que.empty()) {
    int v = que.front();
    que.pop();
    de.push_back(v);
    update(v, que);
    ans += len;
    --len;
  }
  for (int i = 0; i < (int)de.size(); ++i) {
    ve.push_back(make_pair(make_pair(de[i], st[1]), de[i]));
  }
}
int main() {
  scanf("%d", &n);
  int a, b;
  for (int i = 0; i < n - 1; ++i) {
    scanf("%d%d", &a, &b);
    ++degree[a];
    ++degree[b];
    addedge(a, b);
    addedge(b, a);
  }
  st[0] = bfs(1, d[0]);
  st[1] = bfs(st[0], d[0]);
  bfs(st[1], d[1]);
  cut();
  dem();
  cout << ans << endl;
  for (int i = 0; i < (int)ve.size(); ++i) {
    printf("%d %d %d\n", ve[i].first.first, ve[i].first.second, ve[i].second);
  }
  return 0;
}
