#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int DY4[]{1, 0, -1, 0}, DX4[]{0, -1, 0, 1};
constexpr int DY8[]{1, 1, 0, -1, -1, -1, 0, 1};
constexpr int DX8[]{0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U>
inline bool chmax(T& a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U>
inline bool chmin(T& a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int n; cin >> n;
  vector<vector<int>> graph(n);
  REP(_, n - 1) {
    int x, y; cin >> x >> y; --x; --y;
    graph[x].emplace_back(y);
    graph[y].emplace_back(x);
  }
  vector<priority_queue<int>> que(n);
  auto f = [&](auto&& f, int par, int ver) -> int {
    if (par != -1) graph[ver].erase(find(ALL(graph[ver]), par));
    if (graph[ver].empty()) return 1;
    if (graph[ver].size() == 1) {
      int res = f(f, ver, graph[ver].front()) + 1;
      que[ver].swap(que[graph[ver].front()]);
      if (!que[ver].empty()) {
        res += que[ver].top(); que[ver].pop();
      }
      return res;
    }
    int top1 = 0, top2 = 0;
    for (int e : graph[ver]) {
      const int child = f(f, ver, e);
      if (child > top1) {
        que[ver].emplace(top2);
        top2 = top1;
        top1 = child;
      } else if (child > top2) {
        que[ver].emplace(top2);
        top2 = child;
      } else {
        que[ver].emplace(child);
      }
      if (que[ver].size() < que[e].size()) swap(que[ver], que[e]);
      for (; !que[e].empty(); que[e].pop()) que[ver].emplace(que[e].top());
    }
    return top1 + top2 + 1;
  };
  cout << f(f, -1, 0) << '\n';
  return 0;
}