#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
const int N = 2e5 + 5;
const long long int mod = 1e9 + 7;
const long long int Mod = 998244353;
const long double Pi = acos(-1);
const long long int Inf = 4e18;
using namespace std;
vector<int> mark(N);
vector<int> g[N], ans[N], par(N);
vector<bool> vis(N);
map<pair<int, int>, int> q;
void Dfs(int t) {
  vis[t] = true;
  int in = q[{par[t], t}];
  int mex;
  if (mark[in] == 1)
    mex = 2;
  else
    mex = 1;
  for (auto u : g[t]) {
    if (!vis[u]) {
      par[u] = t;
      int idx = q[{t, u}];
      mark[idx] = mex;
      mex++;
      if (mex == mark[in]) mex++;
      Dfs(u);
    }
  }
}
void TestCase() {
  int n;
  cin >> n;
  for (int i = 1, u, v; i < n; i++) {
    cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
    q[{u, v}] = i;
    q[{v, u}] = i;
  }
  int dmax = 0, root = -1, cur = 1;
  for (int i = 1; i <= n; i++) {
    if ((int)g[i].size() > dmax) {
      dmax = (int)g[i].size();
      root = i;
    }
  }
  for (int i = 1; i <= n; i++) {
    vis[i] = false;
    mark[i] = N;
  }
  vis[root] = true;
  for (auto u : g[root]) {
    int in = q[{root, u}];
    par[u] = root;
    mark[in] = cur;
    cur++;
    Dfs(u);
  }
  for (int i = 1; i < n; i++) ans[mark[i]].push_back(i);
  cout << dmax << "\n";
  for (int i = 1; i <= dmax; i++) {
    cout << (int)ans[i].size() << " ";
    for (auto u : ans[i]) cout << u << " ";
    cout << "\n";
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ;
  int T = 1;
  while (T--) {
    TestCase();
  }
  return 0;
}
