#include <bits/stdc++.h>
using namespace std;
const int MAXN = 400000;
const int MAXM = 200000;
const int INF = 1000000010;
const long long int MOD = 1000000007;
const long long int P = 31;
const double EPS = 1e-6;
int N;
vector<pair<int, int> > e;
bool rep[MAXN] = {false};
set<int> g[MAXN];
vector<int> gd[MAXN];
set<int> busy[MAXN];
vector<int> ans[MAXN];
int ansd = 0;
void assign(int id, int t) {
  ans[t].push_back(id);
  busy[e[id].first].insert(t);
  busy[e[id].second].insert(t);
  g[e[id].first].erase(id);
  g[e[id].second].erase(id);
}
void make_gd(int u, int p = -1) {
  int id, v;
  for (auto it = g[u].begin(); it != g[u].end(); it++) {
    id = *it;
    v = (u == e[id].first ? e[id].second : e[id].first);
    if (v != p) {
      gd[u].push_back(v);
      make_gd(v, u);
    }
  }
}
void dfs(int u) {
  int ptr = 1;
  while (!g[u].empty()) {
    if (!busy[u].count(ptr)) {
      assign(*g[u].begin(), ptr);
      ansd = max(ansd, ptr);
    }
    ptr++;
  }
  for (auto it = gd[u].begin(); it != gd[u].end(); it++) dfs(*it);
}
int main() {
  ios_base::sync_with_stdio(false);
  scanf("%d", &N);
  int u, v;
  e.resize(N);
  for (int i = 1; i < N; i++) {
    scanf("%d %d", &u, &v);
    e[i] = make_pair(u, v);
    g[u].insert(i);
    g[v].insert(i);
  }
  make_gd(1);
  dfs(1);
  printf("%d\n", ansd);
  for (int i = 1; i <= ansd; i++) {
    printf("%d ", ans[i].size());
    for (auto it = ans[i].begin(); it != ans[i].end(); it++) printf("%d ", *it);
    printf("\n");
  }
  return 0;
}
