#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("-Ofast")
const int N = 1e5 + 5;
const int mod = 1e9 + 7;
vector<vector<pair<long long int, long long int> > > adj;
vector<vector<long long int> > repair;
long long int modexp(long long int a, long long int b, long long int mod) {
  long long int x = 1;
  while (b) {
    if (b & 1) x = ((x % mod) * (a % mod)) % mod;
    a = ((a % mod) * (a % mod)) % mod;
    b = b / 2;
  }
  return x;
}
void rf() {}
void dfs(long long int node, long long int par, long long int arrival_time) {
  long long int time = 0;
  for (auto x : adj[node]) {
    if (x.first != par) {
      ++time;
      if (time == arrival_time) ++time;
      repair[time].push_back(x.second);
      dfs(x.first, node, time);
    }
  }
}
void solve() {
  long long int n;
  cin >> n;
  adj = vector<vector<pair<long long int, long long int> > >(n + 1);
  repair = vector<vector<long long int> >(2 * n);
  for (int i = 0; i < n - 1; ++i) {
    long long int v1, v2;
    cin >> v1 >> v2;
    adj[v1].push_back({v2, i + 1});
    adj[v2].push_back({v1, i + 1});
  }
  dfs(1, -1, -1);
  int non_empty = 0;
  for (auto x : repair) {
    non_empty += (!x.empty());
  }
  cout << non_empty << "\n";
  for (int i = 1; i <= n; ++i) {
    if (!repair[i].empty()) {
      cout << repair[i].size() << " ";
      for (auto x : repair[i]) cout << x << " ";
      cout << "\n";
    }
  }
}
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  while (t--) {
    solve();
  }
}
