#include <bits/stdc++.h>
using namespace std;
long long int INF = 1e9 + 5;
long long int mod = 998244353;
long long int nax = 2e5;
vector<vector<long long int>> g(nax + 1), days(nax + 1);
map<pair<long long int, long long int>, long long int> mp;
void dfs(long long int node, long long int pa, long long int k,
         long long int no) {
  long long int x = 1;
  for (auto child : g[node]) {
    if (x == no) {
      x++;
    }
    if (child != pa) {
      days[x].push_back(mp[{child, node}]);
      dfs(child, node, k, x++);
    }
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long int n;
  cin >> n;
  for (long long int i = 0; i < n - 1; i++) {
    long long int u, v;
    cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
    mp[{u, v}] = mp[{v, u}] = i + 1;
  }
  long long int k = 0;
  for (long long int node = 1; node <= n; ++node) {
    k = max(k, (long long int)g[node].size());
  }
  dfs(1, 0, k, 0);
  cout << k << "\n";
  for (long long int i = 1; i <= k; i++) {
    cout << days[i].size() << " ";
    for (auto ele : days[i]) {
      cout << ele << " ";
    }
    cout << "\n";
  }
}
