#include<bits/stdc++.h>

using namespace std;

int main() {
#ifndef LOCAL
  freopen("darb.in", "r", stdin);
  freopen("darb.out", "w", stdout);
#endif
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int n;
  cin >> n;
  vector<vector<int> > g(n);
  for (int i = 0; i < n - 1; i++) {
    int u;
    int v;
    cin >> u >> v;
    --u;
    --v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  vector<int> d(n, -1);
  queue<int> q;
  d[0] = 0;
  q.push(0);
  for (
    ;
    q.size()
    ;
  ) {
    auto u = q.front();
    q.pop();
    for (auto v: g[u]) {
      if (d[v] == -1) {
        d[v] = d[u] + 1;
        q.push(v);
      }
    }
  }
  auto i = max_element(d.begin(), d.end()) - d.begin();
  for (auto &e: d) {
    e = -1;
  }
  d[i] = 0;
  q.push(i);
  for (
    ;
    q.size()
    ;
  ) {
    auto u = q.front();
    q.pop();
    for (auto v: g[u]) {
      if (d[v] == -1) {
        d[v] = d[u] + 1;
        q.push(v);
      }
    }
  }
  cout << *max_element(d.begin(), d.end()) + 1 << '\n';
  return 0;
}