#include <bits/stdc++.h>
using namespace std;
void dfs(long long p, vector<vector<long long> > &answ,
         vector<vector<pair<long long, long long> > > &g, long long cur,
         vector<long long> &not_use, vector<long long> &step) {
  for (long long i = 0; i < g[cur].size(); i++) {
    if (g[cur][i].first != p) {
      if (step[cur] == not_use[cur]) step[cur]++;
      answ[step[cur]].push_back(g[cur][i].second + 1);
      not_use[g[cur][i].first] = step[cur];
      dfs(cur, answ, g, g[cur][i].first, not_use, step);
      step[cur]++;
    }
  }
}
int main() {
  long long n;
  cin >> n;
  vector<vector<pair<long long, long long> > > g(n);
  vector<long long> verts(n, 0);
  for (long long i = 0; i < n - 1; i++) {
    long long one, two;
    cin >> one >> two;
    g[one - 1].push_back(make_pair(two - 1, i));
    g[two - 1].push_back(make_pair(one - 1, i));
    verts[one - 1]++;
    verts[two - 1]++;
  }
  long long num_size = 0;
  vector<long long> not_use(n);
  not_use[0] = -1;
  vector<long long> step(n, 0);
  for (long long i = 0; i < n; i++) {
    num_size = max(num_size, verts[i]);
  }
  vector<vector<long long> > answ(num_size);
  cout << num_size << endl;
  dfs(-1, answ, g, 0, not_use, step);
  for (auto &x : answ) {
    cout << x.size() << " ";
    for (auto t : x) cout << t << " ";
    cout << endl;
  }
  cout << endl;
  cin >> n;
  return 0;
}
