#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void gmin(T &x, const T &y) {
  if (x > y) x = y;
}
template <class T>
inline void gmax(T &x, const T &y) {
  if (x < y) x = y;
}
const int BufferSize = 1 << 16;
char buffer[BufferSize], *Bufferhead, *Buffertail;
bool Terminal;
inline char Getchar() {
  if (Bufferhead == Buffertail) {
    int l = fread(buffer, 1, BufferSize, stdin);
    if (!l) {
      Terminal = 1;
      return 0;
    }
    Buffertail = (Bufferhead = buffer) + l;
  }
  return *Bufferhead++;
}
template <class T>
inline bool read(T &x) {
  x = 0;
  char c = Getchar(), rev = 0;
  while (c < '0' || c > '9') {
    c = Getchar();
    rev |= c == '-';
    if (Terminal) return 0;
  }
  while (c >= '0' && c <= '9') x = x * 10 + c - '0', c = Getchar();
  if (c == '.') {
    c = Getchar();
    double t = 0.1;
    while (c >= '0' && c <= '9')
      x = x + (c - '0') * t, c = Getchar(), t = t / 10;
  }
  x = rev ? -x : x;
  return 1;
}
template <class T1, class T2>
inline bool read(T1 &x, T2 &y) {
  return read(x) & read(y);
}
template <class T1, class T2, class T3>
inline bool read(T1 &x, T2 &y, T3 &z) {
  return read(x) & read(y) & read(z);
}
template <class T1, class T2, class T3, class T4>
inline bool read(T1 &x, T2 &y, T3 &z, T4 &w) {
  return read(x) & read(y) & read(z) & read(w);
}
inline bool reads(char *x) {
  char c = Getchar();
  while (c < 33 || c > 126) {
    c = Getchar();
    if (Terminal) return 0;
  }
  while (c >= 33 && c <= 126) (*x++) = c, c = Getchar();
  *x = 0;
  return 1;
}
template <class T>
inline void print(T x, const char c = '\n') {
  if (!x) {
    putchar('0');
    putchar(c);
    return;
  }
  if (x < 0) putchar('-'), x = -x;
  int m = 0, a[20];
  while (x) a[m++] = x % 10, x /= 10;
  while (m--) putchar(a[m] + '0');
  putchar(c);
}
const int inf = 0x3f3f3f3f;
const int N = 200005, M = 100005, mod = 1e9 + 7;
template <class T, class S>
inline void ch(T &x, const S y) {
  x = (x + y) % mod;
}
inline int exp(int x, int y, const int mod = ::mod) {
  int ans = 1;
  while (y) {
    if (y & 1) ans = (long long)ans * x % mod;
    x = (long long)x * x % mod;
    y >>= 1;
  }
  return ans;
}
struct node {
  int x, y, ty;
};
int n, rt, srt, last;
vector<int> g[N], id;
vector<node> ans;
bool vis[N];
int findroot(int x, int f = -1) {
  int tmp = 0, res = 1;
  for (int y : g[x]) {
    if (y == f) continue;
    int t = findroot(y, x);
    res += t;
    gmax(tmp, t);
  }
  gmax(tmp, n - res);
  if (tmp <= n / 2) id.push_back(x);
  return res;
}
void push(int x, int y, int ty) {
  if (x == y || y == ty || x == ty) return;
  ans.push_back((node){x, y, ty});
}
void dfs(int x, int f) {
  vis[x] = 1;
  push(rt, last, x);
  push(x, f, srt);
  last = x;
  for (int y : g[x])
    if (!vis[y]) dfs(y, x);
}
int main() {
  read(n);
  for (int i = 1; i < n; i++) {
    int x, y;
    read(x, y);
    g[x].push_back(y);
    g[y].push_back(x);
  }
  findroot(1);
  for (int i : id) vis[i] = 1;
  for (int i : id) {
    rt = i;
    for (int x : g[i])
      if (!vis[x]) {
        srt = last = x;
        dfs(x, i);
        push(rt, last, srt);
      }
  }
  printf("%d\n", ((int)ans.size()));
  for (node i : ans) printf("%d %d %d\n", i.x, i.y, i.ty);
  return 0;
}
