#include <bits/stdc++.h>
using namespace std;
vector<vector<int> > g;
vector<char> used;
vector<long long> distArr, fArr, sArr;
long long A, B, diameter;
long long answer = 0;
struct step {
  int a, b, d;
  friend ostream& operator<<(ostream& s, const step& v);
};
ostream& operator<<(ostream& s, const step& v) {
  s << v.a << " " << v.b << " " << v.d;
  return s;
}
vector<step> arr;
void dfs(int v, long long dist, vector<long long>& dArr, long long& cur) {
  dArr[v] = dist;
  if (dArr[cur] < dist) cur = v;
  for (int i = 0; i < (int)g[v].size(); i++) {
    int to = g[v][i];
    if (!used[to]) {
      used[to] = true;
      dfs(to, dist + 1, dArr, cur);
    }
  }
}
void dfs2(int v, long long dist, bool flag) {
  if (!flag) {
    sArr[v] = dist;
  }
  for (int i = 0; i < (int)g[v].size(); i++) {
    int to = g[v][i];
    if (!used[to]) {
      used[to] = true;
      dfs2(to, dist + 1, flag);
    }
  }
  if (fArr[v] + sArr[v] > diameter) {
    step temp;
    if (fArr[v] > sArr[v]) {
      temp.a = A + 1;
      answer += fArr[v];
    } else {
      temp.a = B + 1;
      answer += sArr[v];
    }
    temp.b = v + 1;
    temp.d = v + 1;
    arr.push_back(temp);
  }
  if (fArr[v] + sArr[v] == diameter && flag && v != A) {
    step temp;
    temp.a = A + 1;
    temp.d = v + 1;
    temp.b = v + 1;
    answer += fArr[v];
    arr.push_back(temp);
  } else if (fArr[v] + sArr[v] == diameter)
    used[v] = false;
}
int main() {
  int n;
  cin >> n;
  g.assign(n, vector<int>());
  for (int i = 0; i < n - 1; i++) {
    int from, to;
    cin >> from >> to;
    g[from - 1].push_back(to - 1);
    g[to - 1].push_back(from - 1);
  }
  used.assign(n, false);
  used[0] = true;
  distArr.assign(n, 0);
  A = 0;
  B = 0;
  dfs(0, 0, distArr, A);
  used.assign(n, false);
  used[A] = true;
  fArr.assign(n, 0);
  sArr.assign(n, 0);
  dfs(A, 0, fArr, B);
  diameter = fArr[B];
  used.assign(n, false);
  used[B] = true;
  dfs2(B, 0, false);
  dfs2(A, 0, true);
  cout << answer << endl;
  for (int i = 0; i < (int)arr.size(); i++) cout << arr[i] << endl;
  return 0;
}
