#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
void rset();
void init_test();
void solve();
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed;
  cout.precision(20);
  init_test();
  return 0;
}
template <typename T>
void chmin(T& a, T b) {
  if (a > b) a = b;
}
template <typename T>
void chmax(T& a, T b) {
  if (a < b) a = b;
}
template <typename T>
void MACRO_rdv2_Init(int n, T& t) {
  t.resize(n);
}
template <typename First, typename... Rest>
void MACRO_rdv2_Init(int n, First& first, Rest&... rest) {
  first.resize(n);
  MACRO_rdv2_Init(n, rest...);
}
template <typename T>
void MACRO_rdv2_Scan(int p, T& t) {
  std::cin >> t[p];
}
template <typename First, typename... Rest>
void MACRO_rdv2_Scan(int p, First& first, Rest&... rest) {
  std::cin >> first[p];
  MACRO_rdv2_Scan(p, rest...);
}
template <typename T>
void wrv(const vector<T>& v) {
  for (int(__ii) = (0); (__ii) < (((int)v.size())); ++(__ii)) {
    if (__ii) cout << ' ';
    cout << v[__ii];
  }
  cout << '\n';
}
template <typename T>
void wrm(const vector<vector<T>>& v) {
  for (int(__ii) = (0); (__ii) < (((int)v.size())); ++(__ii)) {
    for (int(__jj) = (0); (__jj) < (v[__ii].size()); ++(__jj)) {
      if (__jj) cout << ' ';
      cout << v[__ii][__jj];
    }
    cout << '\n';
  }
}
template <typename T>
void sc(T& x) {
  cin >> x;
}
template <typename Head, typename... Tail>
void sc(Head& head, Tail&... tail) {
  cin >> head;
  sc(tail...);
}
template <typename T>
void wr(const T& x) {
  cout << x << '\n';
}
template <typename Head, typename... Tail>
void wr(const Head& head, const Tail&... tail) {
  cout << head << ' ';
  wr(tail...);
}
template <typename T>
void wrf(const T& x) {
  cout << x << endl;
}
template <typename Head, typename... Tail>
void wrf(const Head& head, const Tail&... tail) {
  cout << head << ' ';
  wrf(tail...);
}
template <typename T>
void debug_out(const T& x) {
  cerr << x << '\n';
}
template <typename Head, typename... Tail>
void debug_out(const Head& head, const Tail&... tail) {
  cerr << head << ' ';
  debug_out(tail...);
}
template <typename... T>
void err(const T&... cod) {
  wr(cod...);
  exit(0);
}
const int N = 2e5 + 10;
int n;
vector<pair<int, int>> g[N];
vector<int> ans[N];
set<int> avail[N];
void dfs(int u, int p) {
  for (auto v : g[u]) {
    if (v.first == p) continue;
    int d = *avail[u].begin();
    ans[d].push_back(v.second + 1);
    avail[u].erase(d);
    avail[v.first].erase(d);
    dfs(v.first, u);
  }
}
void solve() {
  cin >> n;
  for (int(i) = (0); (i) < (n - 1); ++(i)) {
    int u, v;
    sc(u, v);
    --u, --v;
    g[u].push_back(make_pair(v, i));
    g[v].push_back(make_pair(u, i));
  }
  int mxd = 0;
  for (int(i) = (0); (i) < (n); ++(i)) {
    for (int(j) = (0); (j) < (((int)g[i].size())); ++(j)) avail[i].insert(j);
    chmax(mxd, ((int)g[i].size()));
  }
  dfs(0, -1);
  wr(mxd);
  for (int(i) = (0); (i) < (mxd); ++(i)) {
    cout << ((int)ans[i].size()) << ' ';
    wrv(ans[i]);
  }
}
void init_test() {
  int qq = 1;
  while (qq--) solve();
}
