#include <bits/stdc++.h>
using namespace std;
template <typename A, typename B>
string to_string(pair<A, B> p);
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
string to_string(const string& s) { return '"' + s + '"'; }
string to_string(const char& ch) {
  string s = "";
  s += ch;
  return "'" + s + "', ";
}
string to_string(const char* s) { return to_string((string)s); }
string to_string(bool b) { return (b ? "true" : "false"); }
string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}
template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto& x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " +
         to_string(get<2>(p)) + ")";
}
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " +
         to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
void debug_out() { cout << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cout << " " << to_string(H);
  debug_out(T...);
}
const long long mod = (long long)1000000007;
const long long inf = (long long)2e18;
const long long maxn = 2e5 + 10;
set<long long> adj[maxn];
long long n;
map<pair<long long, long long>, long long> mp;
pair<long long, long long> a[maxn];
long long vis[maxn];
long long par[maxn];
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout << fixed << setprecision(9);
  cin >> n;
  42;
  for (long long i = 1; i <= n - 1; ++i) {
    long long u, v;
    cin >> u >> v;
    adj[u].insert(v);
    adj[v].insert(u);
    mp[{u, v}] = i;
    mp[{v, u}] = i;
  }
  long long mx = -1;
  for (long long i = 1; i <= n; ++i) {
    mx = max(mx, ((long long)(adj[i]).size()));
    42;
  }
  queue<long long> q;
  q.push(1);
  vis[1] = 1;
  par[1] = 0;
  vector<long long> ans[mx + 1];
  while (!q.empty()) {
    long long v = q.front();
    q.pop();
    long long day = 1;
    42;
    for (long long u : adj[v]) {
      if (vis[u]) continue;
      if (day == par[v]) ++day;
      ans[day].push_back(mp[{v, u}]);
      par[u] = day;
      ++day;
      q.push(u);
      vis[u] = 1;
    }
  }
  cout << mx << '\n';
  for (long long i = 1; i <= mx; ++i) {
    cout << ((long long)(ans[i]).size()) << " ";
    for (long long& x : ans[i]) {
      cout << x << " ";
    }
    cout << '\n';
  }
  return 0;
}
