#include <bits/stdc++.h>
using namespace std;
const long long inf = (1ll << 62) - 1;
const long long MOD = 1e9 + 7;
const int MAX = 2 * 1e9 + 10;
const int N = 2e5 + 5;
using namespace std;
int bPow(int a, int b) {
  int res = 1;
  while (b) {
    if (b & 1ll) {
      res = 1ll * res * a % MOD;
    }
    b >>= 1;
    a = 1ll * a * a % MOD;
  }
  return res;
}
int gcd(int a, int b) {
  if (a < b) {
    swap(a, b);
  }
  if (b == 0) return a;
  return gcd(b, a % b);
}
vector<int> mpf(N, 0);
void sieve() {
  for (int i = 2; i < N; ++i) {
    if (!mpf[i])
      for (int j = 2 * i; j < N; j += i) {
        mpf[j] = i;
      }
  }
}
vector<vector<pair<int, int>>> adj(N);
vector<int> roads[N];
void dfs(int u, int par, int day) {
  int cur = 0;
  for (auto i : adj[u]) {
    int v = i.first, pos = i.second;
    if (par != v) {
      if (cur == day) cur++;
      roads[cur].push_back(pos);
      dfs(v, u, cur++);
    }
  }
}
void solve() {
  int n;
  cin >> n;
  int maxDays = 0;
  for (int i = 0; i < n - 1; ++i) {
    int u, v;
    cin >> u >> v;
    adj[u].push_back({v, i + 1}), adj[v].push_back({u, i + 1});
    maxDays = max({maxDays, (int)adj[u].size(), (int)adj[v].size()});
  }
  dfs(1, -1, -1);
  cout << maxDays << endl;
  for (int i = 0; i < maxDays; ++i) {
    cout << roads[i].size() << " ";
    for (int it : roads[i]) cout << it << " ";
    cout << endl;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int tc = 1;
  while (tc--) {
    solve();
  }
  return 0;
}
