#include <bits/stdc++.h>
using namespace std;
const int N = 105;
int n, fa[N];
vector<int> e[N];
void dfs(int x, int fas, int dep, int &mx) {
  mx = max(mx, dep);
  for (int y : e[x])
    if (y != fas) dfs(y, x, dep + 1, mx);
}
void dfs2(int x, int fas) {
  fa[x] = fas;
  for (int y : e[x])
    if (y != fas) dfs2(y, x);
}
int main() {
  // freopen("my.txt","w",stdout);
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (int i = 1, x, y; i < n; i++) {
    cin >> x >> y;
    e[x].push_back(y), e[y].push_back(x);
  }
  int rt = -1, mn = n;
  for (int i = 0; i < n; i++) {
    int mx = 0;
    dfs(i, i, 1, mx);
    if (mx < mn) mn = mx, rt = i;
  }
  dfs2(rt, rt);
  cout << 502 << endl;
  for (int x = 0; x < n; x++) {
    int now = x;
    for (int i = 1, op = 0; i <= 128; i *= 4, op = 1 - op) {
      for (int j = 1; j <= i; j++)
        now = fa[now], cout << now << " " << now << " ";
      for (int j = 1; j < i * 2; j++) cout << now << " " << now << " ";
    }
    cout << endl;
  }
  for (int x = 0; x < n; x++) {
    int now = x;
    for (int i = 1, op = 1; i <= 128; i *= 4, op = 1 - op) {
      for (int j = 1; j < i; j++) cout << now << " " << now << " ";
      for (int j = 1; j <= i * 2; j++)
        cout << now << " " << fa[now] << " ", now = fa[now];
    }
    cout << endl;
  }
  return 0;
}