#include <bits/stdc++.h>
using namespace std;

#ifdef _RUTHEN
#include "debug.hpp"
#else
#define show(...) true
#endif

using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); i++)
template <class T> using V = vector<T>;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N;
    cin >> N;
    V<V<int>> G(N);
    rep(i, N - 1) {
        int x, y;
        cin >> x >> y;
        x--, y--;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    auto rec = [&](auto f, int cur, int par, priority_queue<int> &que) -> void {
        for (auto &nex : G[cur]) {
            if (nex == par) continue;
            priority_queue<int> nque;
            f(f, nex, cur, nque);
            while (!nque.empty()) {
                que.push(nque.top());
                nque.pop();
            }
        }
        int v = 1, cnt = 0;
        while (!que.empty() && cnt < 2) {
            cnt++;
            v += que.top();
            que.pop();
        }
        que.push(v);
        return;
    };
    priority_queue<int> que0;
    rec(rec, 0, -1, que0);
    int ans = que0.top();
    cout << ans << '\n';
    return 0;
}