#include <bits/stdc++.h>
using namespace std;
template <class T>
T sqr(T x) {
  return x * x;
}
template <class T>
T gcd(T a, T b) {
  return (b != 0 ? gcd<T>(b, a % b) : a);
}
template <class T>
T lcm(T a, T b) {
  return (a / gcd<T>(a, b) * b);
}
template <class T>
inline T bigmod(T p, T e, T M) {
  if (e == 0) return 1;
  if (e % 2 == 0) {
    long long int t = bigmod(p, e / 2, M);
    return (T)((t * t) % M);
  }
  return (T)((long long int)bigmod(p, e - 1, M) * (long long int)p) % M;
}
template <class T>
inline T bigexp(T p, T e) {
  if (e == 0) return 1;
  if (e % 2 == 0) {
    long long int t = bigexp(p, e / 2);
    return (T)((t * t));
  }
  return (T)((long long int)bigexp(p, e - 1) * (long long int)p);
}
template <class T>
inline T modinverse(T a, T M) {
  return bigmod(a, M - 2, M);
}
int dx4[] = {1, 0, -1, 0};
int dy4[] = {0, 1, 0, -1};
int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1};
int dy8[] = {0, 1, 1, 1, 0, -1, -1, -1};
int nx8[] = {1, 1, -1, -1, 2, 2, -2, -2};
int ny8[] = {2, -2, 2, -2, 1, -1, 1, -1};
int month[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int n, u, v, ind[200005], mx;
vector<int> edges[200005], r_no[200005], d[200005];
void dfs(int u, int v, int no) {
  int c = 0;
  for (int i = 0; i < edges[u].size(); i++) {
    if (edges[u][i] == v) continue;
    if (c + 1 == no) c++;
    ++c;
    d[c].push_back(r_no[u][i]);
    dfs(edges[u][i], u, c);
  }
  return;
}
int main() {
  scanf("%d", &n);
  for (__typeof(n - 1) i = (1); i <= (n - 1); i++) {
    scanf("%d %d", &u, &v);
    edges[u].push_back(v);
    edges[v].push_back(u);
    r_no[u].push_back(i);
    r_no[v].push_back(i);
    ind[u]++;
    ind[v]++;
    mx = max(mx, ind[v]);
    mx = max(mx, ind[u]);
  }
  dfs(1, 0, 0);
  printf("%d\n", mx);
  for (int i = 1; i <= mx; i++) {
    printf("%d", d[i].size());
    for (int j = 0; j < d[i].size(); j++) printf(" %d", d[i][j]);
    printf("\n");
  }
  return 0;
}
