#include <bits/stdc++.h>
using namespace std;
const double PI = 2 * acos(0.0);
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());
const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";
template <class T0, class T1>
inline ostream &operator<<(ostream &out, pair<T0, T1> &a) {
  return out << "{" << a.first << ", " << a.second << "}";
}
template <class T0, class T1>
inline istream &operator>>(istream &in, pair<T0, T1> &a) {
  return in >> a.first >> a.second;
}
template <class T0, class T1, class T2>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << "}";
}
template <class T0, class T1, class T2, class T3>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2, T3> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << ", " << get<3>(a) << "}";
}
template <class T>
inline ostream &operator<<(ostream &out, vector<T> &a) {
  out << "[";
  for (int i = 0; i < int(a.size()); ++i)
    out << a[i] << vector<string>{", ", "]  "}[i + 1 == a.size()];
  return out;
}
void smain();
signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout << setprecision(12) << fixed;
  smain();
  return 0;
}
const int N = 1e5 + 10;
const int oo = 1e6 + 100;
vector<int> g[N];
int dp1[N];
int dp2[N];
void dfs1(int v, int par) {
  int deg = 0;
  for (int to : g[v]) {
    if (to == par) continue;
    deg++;
    dfs1(to, v);
  }
  dp1[v] = 1;
  dp2[v] = 0;
  for (int to : g[v]) {
    if (to == par) continue;
    dp1[v] = max(dp1[v], (dp2[to] + 1));
    dp2[v] = max(dp2[v], (max(dp1[to], dp2[to]) + deg - 1));
  }
}
int ans = 0;
int root = 1;
void dfs2(int v, int par, int u1, int u2) {
  int deg = 0;
  if (v == root) {
    deg = -1;
    u1 = u2 = -oo;
  }
  ans = max(ans, (dp1[v]));
  ans = max(ans, (1 + u2));
  for (int to : g[v]) {
    if (to == par) continue;
    deg++;
  }
  multiset<int> dp2s;
  dp2s.insert(u2 + 1);
  dp2s.insert(1);
  multiset<int> dpall;
  dpall.insert(0);
  dpall.insert(max(u1, u2) + deg - 1);
  for (int to : g[v]) {
    if (to == par) continue;
    dp2s.insert(dp2[to] + 1);
    dpall.insert(max(dp1[to], dp2[to]) + deg - 1);
  }
  for (int to : g[v]) {
    if (to == par) continue;
    dp2s.erase(dp2s.find(dp2[to] + 1));
    dpall.erase(dpall.find(max(dp1[to], dp2[to]) + deg - 1));
    int cdp1 = *dp2s.rbegin();
    int cdp2 = *dpall.rbegin();
    dfs2(to, v, cdp1, cdp2);
    dp2s.insert(dp2[to] + 1);
    dpall.insert(max(dp1[to], dp2[to]) + deg - 1);
  }
}
void smain() {
  int n;
  cin >> n;
  for (int i = 0; i < int(n - 1); ++i) {
    int u, v;
    cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  dfs1(1, -1);
  dfs2(1, -1, -1, -1);
  cout << ans;
}
