#include <bits/stdc++.h>
using namespace std;
using ll = long long;
void dfs(const vector<vector<int>>& g, int a, vector<int>& d, int p) {
  if (a == p) {
    d[a] = 0;
  } else {
    d[a] = d[p] + 1;
  }
  for (int b : g[a]) {
    if (b != p) dfs(g, b, d, a);
  }
}
int main() {
  ios::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<vector<int>> g(n);
  for (int i = 0; i < n - 1; i++) {
    int a, b;
    cin >> a >> b;
    a--;
    b--;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  vector<int> dfb(n);
  dfs(g, 0, dfb, 0);
  int a = 0;
  for (int i = 1; i < n; i++)
    if (dfb[i] > dfb[a]) a = i;
  vector<int> dfa(n);
  dfs(g, a, dfa, a);
  int b = 0;
  for (int i = 1; i < n; i++)
    if (dfa[i] > dfa[b]) b = i;
  dfs(g, b, dfb, b);
  ll val = 0;
  vector<pair<int, int>> ans;
  vector<int> ord;
  for (int i = 0; i < n; i++) {
    if (dfa[i] + dfb[i] == dfa[b]) continue;
    ord.push_back(i);
  }
  sort(ord.begin(), ord.end(),
       [&](int i, int j) { return max(dfa[i], dfb[i]) > max(dfa[j], dfb[j]); });
  for (int i : ord) {
    if (dfa[i] > dfb[i]) {
      val += dfa[i];
      ans.push_back({i, a});
    } else {
      val += dfb[i];
      ans.push_back({i, b});
    }
  }
  ord.clear();
  for (int i = 0; i < n; i++) {
    if (dfa[i] + dfb[i] != dfa[b]) continue;
    ord.push_back(i);
  }
  sort(ord.begin(), ord.end(), [&](int i, int j) { return dfa[i] > dfa[j]; });
  for (int i = 0; i + 1 < ord.size(); i++) {
    val += dfa[ord[i]];
    ans.push_back({ord[i], a});
  }
  cout << val << endl;
  for (auto e : ans) {
    cout << (e.first + 1) << ' ' << (e.second + 1) << ' ' << (e.first + 1)
         << '\n';
  }
}
