#include <bits/stdc++.h>
using namespace std;
int read() {
  int ans = 0, f = 1;
  char c = getchar();
  while (c > '9' || c < '0') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    ans = ans * 10 + c - '0';
    c = getchar();
  }
  return ans * f;
}
const int N = 2e5 + 5;
int n, du[N], head[N], tot, ans;
vector<int> agg[N];
struct Edge {
  int v, ne;
} e[N * 2];
inline void add(int u, int v);
inline void dfs(int u, int fa, int last);
int main() {
  n = read();
  for (int i = 1; i < n; ++i) {
    int u = read(), v = read();
    du[u]++, du[v]++;
    add(u, v);
    add(v, u);
    ans = max(ans, max(du[u], du[v]));
  }
  printf("%d\n", ans);
  dfs(1, -1, 0);
  for (int i = 1; i <= ans; ++i) {
    printf("%d ", agg[i].size());
    for (int j = 0; j < agg[i].size(); ++j) printf("%d ", agg[i][j]);
    printf("\n");
  }
  return 0;
}
inline void add(int u, int v) {
  e[++tot] = (Edge){v, head[u]};
  head[u] = tot;
}
inline void dfs(int u, int fa, int last) {
  int j = 1;
  for (int i = head[u]; i; i = e[i].ne) {
    int v = e[i].v;
    if (v == fa) continue;
    if (j == last) j++;
    agg[j].push_back((i + 1) / 2);
    dfs(v, u, j);
    ++j;
  }
  return;
}
