#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }
#define COLOR(s) ("\x1b[" s "m")


int N;
vector<int> A, B;

vector<vector<int>> graph;
vector<int> sz;

void dfsSz(int u, int p) {
  for (const int v : graph[u]) if (p != v) {
    dfsSz(v, u);
    sz[u] += sz[v];
  }
}

int H;
map<vector<int>, int> ids;
vector<int> dp;
vector<vector<int>> subtree;
vector<vector<int>> ans;

vector<int> identity() {
  vector<int> perm(N);
  for (int u = 0; u < N; ++u) perm[u] = u;
  return perm;
}
void sw(vector<int> &perm, int u, int v) {
  assert(subtree[u].size() == subtree[v].size());
  for (int j = 0; j < (int)subtree[u].size(); ++j) {
    swap(perm[subtree[u][j]], perm[subtree[v][j]]);
  }
}

void dfs(int u, int p) {
  vector<pair<int, int>> hvs;
  for (const int v : graph[u]) if (p != v) {
    dfs(v, u);
    hvs.emplace_back(dp[v], v);
  }
  sort(hvs.begin(), hvs.end());
  const int hvsLen = hvs.size();
// cerr<<u<<" "<<p<<": "<<hvs<<endl;
  for (int j = 0, k = 0; j < hvsLen; j = k) {
    for (; k < hvsLen && hvs[j].first == hvs[k].first; ++k) {}
    // permute us[j, k)
    if (k - j >= 2) {
      auto perm = identity();
      sw(perm, hvs[j].second, hvs[j + 1].second);
      ans.push_back(perm);
    }
    if (k - j >= 3) {
      auto perm = identity();
      for (int l = j; l < k - 1; ++l) sw(perm, hvs[l].second, hvs[l + 1].second);
      ans.push_back(perm);
    }
  }
  
  vector<int> hs(hvsLen);
  for (int j = 0; j < hvsLen; ++j) hs[j] = hvs[j].first;
  if (!ids.count(hs)) ids[hs] = H++;
  dp[u] = ids[hs];
  
  subtree[u] = {u};
  for (const auto &hv : hvs) {
    const int v = hv.second;
    subtree[u].insert(subtree[u].end(), subtree[v].begin(), subtree[v].end());
  }
}

int main() {
  for (; ~scanf("%d", &N); ) {
    A.resize(N - 1);
    B.resize(N - 1);
    for (int i = 0; i < N - 1; ++i) {
      scanf("%d%d", &A[i], &B[i]);
      --A[i];
      --B[i];
    }
    
    graph.assign(N, {});
    for (int i = 0; i < N - 1; ++i) {
      graph[A[i]].push_back(B[i]);
      graph[B[i]].push_back(A[i]);
    }
    sz.assign(N, 1);
    dfsSz(0, -1);
    
    H = 0;
    ids.clear();
    dp.assign(N, -1);
    subtree.assign(N, {});
    ans.clear();
    for (int u = 0; ; ) {
      int vm = -1;
      for (const int v : graph[u]) if (!~vm || sz[vm] < sz[v]) {
        vm = v;
      }
      if (~vm && 2 * sz[vm] > sz[u]) {
        sz[u] -= sz[vm];
        sz[vm] += sz[u];
        u = vm;
      } else if (~vm && 2 * sz[vm] == sz[u]) {
        dfs(u, vm);
        dfs(vm, u);
        if (dp[u] == dp[vm]) {
          auto perm = identity();
          sw(perm, u, vm);
          ans.push_back(perm);
        }
        break;
      } else {
        dfs(u, -1);
        break;
      }
    }
// cerr<<"subtree = "<<subtree<<endl;
    
    if (!ans.size()) {
      ans.push_back(identity());
    }
    
    printf("%d\n", (int)ans.size());
    for (const auto &perm : ans) {
      for (int u = 0; u < N; ++u) {
        if (u) printf(" ");
        printf("%d", perm[u] + 1);
      }
      puts("");
    }
  }
  return 0;
}