#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const int MOD2 = 1007681537;
const int INF = (int)1e9;
const long long LINF = (long long)1e18;
const long double PI = acos((long double)-1);
const long double EPS = 1e-9;
inline long long gcd(long long a, long long b) {
  long long r;
  while (b) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
inline long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
inline long long fpow(long long n, long long k, int p = MOD) {
  long long r = 1;
  for (; k; k >>= 1) {
    if (k & 1) r = r * n % p;
    n = n * n % p;
  }
  return r;
}
template <class T>
inline int chkmin(T& a, const T& val) {
  return val < a ? a = val, 1 : 0;
}
template <class T>
inline int chkmax(T& a, const T& val) {
  return a < val ? a = val, 1 : 0;
}
inline long long isqrt(long long k) {
  long long r = sqrt(k) + 1;
  while (r * r > k) r--;
  return r;
}
inline long long icbrt(long long k) {
  long long r = cbrt(k) + 1;
  while (r * r * r > k) r--;
  return r;
}
inline void addmod(int& a, int val, int p = MOD) {
  if ((a = (a + val)) >= p) a -= p;
}
inline void submod(int& a, int val, int p = MOD) {
  if ((a = (a - val)) < 0) a += p;
}
inline int mult(int a, int b, int p = MOD) { return (long long)a * b % p; }
inline int inv(int a, int p = MOD) { return fpow(a, p - 2, p); }
inline int sign(long double x) { return x < -EPS ? -1 : x > +EPS; }
inline int sign(long double x, long double y) { return sign(x - y); }
const int maxn = 2e5 + 5;
int n;
vector<int> adj[maxn];
int del[maxn];
int size[maxn];
vector<pair<int, pair<int, int> > > res;
void dfs(int u, int p) {
  size[u] = 1;
  for (int i = 0; i < adj[u].size(); i++) {
    int v = adj[u][i];
    if (v != p && !del[v]) {
      dfs(v, u);
      size[u] += size[v];
    }
  }
}
int findcentroid(int u) {
  int p = -1;
  dfs(u, -1);
  int cap = size[u] >> 1;
  while (1) {
    bool found = false;
    for (int i = 0; i < adj[u].size(); i++) {
      int v = adj[u][i];
      if (v != p && !del[v] && size[v] > cap) {
        found = true;
        p = u;
        u = v;
        break;
      }
    }
    if (!found) return u;
  }
}
int lst;
void dfs(int u, int p, int ac, int w) {
  for (int i = (0); i < (int((adj[u]).size())); i++) {
    int v = adj[u][i];
    if (v != p) {
      dfs(v, u, ac, w);
      if (p != ac && u != w) {
        res.push_back(make_pair(ac, make_pair(lst, v)));
        res.push_back(make_pair(v, make_pair(u, w)));
        lst = v;
      }
    }
  }
}
void solve() {
  cin >> n;
  for (int i = (0); i < (n - 1); i++) {
    int u, v;
    cin >> u >> v;
    u--, v--;
    adj[u].push_back(v), adj[v].push_back(u);
  }
  int u = findcentroid(0);
  int w = -1;
  for (int i = (0); i < (int((adj[u]).size())); i++) {
    int v = adj[u][i];
    if (size[v] + size[v] == n) {
      w = v;
    }
  }
  if (w == -1) {
    for (int i = (0); i < (int((adj[u]).size())); i++) {
      int v = adj[u][i];
      lst = v;
      dfs(v, u, u, v);
      if (lst != v) {
        res.push_back(make_pair(u, make_pair(lst, v)));
      }
    }
  } else {
    for (int it = (0); it < (2); it++) {
      for (int i = (0); i < (int((adj[u]).size())); i++) {
        int v = adj[u][i];
        if (v != w) {
          lst = v;
          dfs(v, u, u, v);
          if (lst != v) {
            res.push_back(make_pair(u, make_pair(lst, v)));
          }
        }
      }
      swap(u, w);
    }
  }
  cout << int((res).size()) << "\n";
  for (int i = (0); i < (int((res).size())); i++) {
    cout << res[i].first + 1 << " " << res[i].second.first + 1 << " "
         << res[i].second.second + 1 << "\n";
  }
}
int main() {
  int JUDGE_ONLINE = 1;
  if (fopen("in.txt", "r")) {
    JUDGE_ONLINE = 0;
    assert(freopen("in.txt", "r", stdin));
  } else {
    ios_base::sync_with_stdio(0), cin.tie(0);
  }
  solve();
  if (!JUDGE_ONLINE) {
  }
  return 0;
}
