#include <bits/stdc++.h>
using namespace std;
vector<vector<long long> > adj;
vector<long long> p;
unordered_set<long long> dia;
pair<long long, long long> dfs(long long x, long long pa, long long d) {
  p[x] = pa;
  pair<long long, long long> an = {d, x};
  for (long long i = 0; i < adj[x].size(); i++) {
    if (adj[x][i] != pa) an = max(an, dfs(adj[x][i], x, d + 1));
  }
  return an;
}
pair<long long, long long> dfs1(long long x, long long pa, long long d) {
  p[x] = pa;
  pair<long long, long long> an = {d, x};
  for (long long i = 0; i < adj[x].size(); i++) {
    if (adj[x][i] != pa && dia.find(adj[x][i]) == dia.end())
      an = max(an, dfs(adj[x][i], x, d + 1));
  }
  return an;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n;
  cin >> n;
  p.resize(n);
  adj.resize(n);
  for (long long i = 0; i < n - 1; i++) {
    long long x, y;
    cin >> x >> y;
    --x, --y;
    adj[x].push_back(y);
    adj[y].push_back(x);
  }
  pair<long long, long long> d1 = dfs(0, -1, 0);
  pair<long long, long long> d2 = dfs(d1.second, -1, 0);
  long long y = d2.second;
  while (y != d1.second) {
    dia.insert(y);
    y = p[y];
  }
  dia.insert(d1.second);
  if (d2.first == (n - 1)) {
    cout << n - 1 << endl << d2.second + 1 << " " << d1.second + 1 << " ";
    for (int i = 1; i <= n; i++)
      if (i != (d2.second + 1) && i != (d1.second + 1)) {
        cout << i << endl;
        break;
      }
    return 0;
  }
  pair<long long, long long> c = {0, 0};
  for (auto it : dia) {
    pair<long long, long long> pr = dfs1(it, -1, 0);
    c = max(c, pr);
  }
  cout << c.first + d2.first << endl
       << c.second + 1 << " " << d2.second + 1 << " " << d1.second + 1 << endl;
  return 0;
}
