#include <bits/stdc++.h>
using namespace std;
const long long N = 2e5;
const long long mod = 998244353;
vector<vector<long long> > day(N + 1);
vector<vector<pair<long long, long long> > > adj(N + 1);
long long vis[N + 1], col[N + 1];
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n, mx = 0;
  cin >> n;
  for (long long i = 1; i < n; i++) {
    long long u, v;
    cin >> u >> v;
    adj[u].push_back({v, i});
    adj[v].push_back({u, i});
  }
  queue<long long> q;
  q.push(1);
  vis[1] = 1;
  while (!q.empty()) {
    long long v = q.front(), cnt = 1;
    q.pop();
    for (long long j = 0; j < adj[v].size(); j++) {
      long long u = adj[v][j].first, id = adj[v][j].second;
      if (vis[u] == 0) {
        vis[u] = 1;
        if (col[v] == cnt) cnt++;
        col[u] = cnt;
        day[cnt].push_back(id);
        mx = max(mx, cnt);
        cnt++;
        q.push(u);
      }
    }
  }
  cout << mx << "\n";
  for (long long i = 1; i <= mx; i++) {
    cout << day[i].size() << " ";
    for (long long j = 0; j < day[i].size(); j++) cout << day[i][j] << " ";
    cout << "\n";
  }
  return 0;
}
