#include <bits/stdc++.h>
using namespace std;
const int N = 200005;
int d[3][N], n, x, y;
long long ans;
vector<int> e[N], out;
queue<int> q;
void bfs(int *dis, int b) {
  for (int i = 1; i <= n; i++) dis[i] = -1;
  dis[b] = 0;
  q.push(b);
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    for (auto v : e[u]) {
      if (dis[v] == -1) {
        dis[v] = dis[u] + 1;
        q.push(v);
      }
    }
  }
}
int dfs(int u, int f, int t) {
  int zh = 0;
  for (auto v : e[u]) {
    if (v == f) continue;
    zh |= dfs(v, u, t);
  }
  if (u == y) zh = 1;
  if (t == 0 && zh == 0) {
    out.push_back(u);
    out.push_back(d[1][u] > d[2][u] ? x : y);
    out.push_back(u);
    ans += max(d[1][u], d[2][u]);
  }
  if (t == 1 && zh == 1 && f) {
    out.push_back(u);
    out.push_back(x);
    out.push_back(u);
    ans += d[1][u];
  }
  return zh;
}
int main() {
  scanf("%d", &n);
  for (int i = 1; i < n; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    e[u].push_back(v);
    e[v].push_back(u);
  }
  bfs(d[0], 1);
  for (int i = 1; i <= n; i++)
    if (d[0][i] > d[0][x]) x = i;
  bfs(d[1], x);
  for (int i = 1; i <= n; i++)
    if (d[1][i] > d[1][y]) y = i;
  bfs(d[2], y);
  dfs(x, 0, 0);
  dfs(x, 0, 1);
  printf("%I64d\n", ans);
  for (int i = 0; i < out.size(); i += 3)
    printf("%d %d %d\n", out[i], out[i + 1], out[i + 2]);
  return 0;
}
