#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>

using namespace std;

class Node
{
public:
    Node() : h(0) {}

    int h;
    vector<int> child;
};

int root;
int max_path;
vector<Node> nodes;

bool mycmp(int a, int b)
{
    return (nodes[b].h < nodes[a].h);
}

int DFS(int idx)
{
    if (nodes[idx].child.empty()) {
        nodes[idx].h = 1;
        return 1;
    }

    for (int i=0;i<nodes[idx].child.size();i++) {
        nodes[idx].h = max(nodes[idx].h, DFS(nodes[idx].child[i]) + 1);
    }
    sort(nodes[idx].child.begin(), nodes[idx].child.end(), mycmp);
    if (nodes[idx].child.size() == 1) {
        max_path = max(max_path, nodes[nodes[idx].child[0]].h);
    }
    else {
        max_path = max(max_path, nodes[nodes[idx].child[0]].h + nodes[nodes[idx].child[1]].h);
    }
    return nodes[idx].h;
}

void calc(int idx)
{
    for (int i=0;i<nodes[idx].child.size();i++) {
        nodes[idx].h = max(nodes[idx].h, DFS(nodes[idx].child[i]) + 1);
    }
    sort(nodes[idx].child.begin(), nodes[idx].child.end(), mycmp);
    if (nodes[idx].child.size() == 1) {
        max_path = max(max_path, nodes[nodes[idx].child[0]].h);
    }
    else {
        max_path = max(max_path, nodes[nodes[idx].child[0]].h + nodes[nodes[idx].child[1]].h);
    }
}

int main()
{
    int n;
    int parent, child;
    while (cin >> n) {
        vector<int> pp(n, -1);
        root = -1;
        max_path = 0;
        nodes.clear();
        for (int i=0;i<n;i++) {
            Node node;
            nodes.push_back(node);
        }
        for (int i=0;i<n-1;i++) {
            cin >> parent >> child;
            pp[child] = parent;
            nodes[parent].child.push_back(child);
        }
        for (int i=0;i<n;i++) {
            if (pp[i] == -1) {
                root = i;
                break;
            }
        }
        calc(root);
        cout << max_path << endl;
    }
    return 0;
}