//Boundary Traversal of a Binary Tree
#include <iostream>
#include <vector>
using namespace std;

struct Node {
    int val;
    Node *left, *right;
    Node(int x) : val(x), left(nullptr), right(nullptr) {}
};

void leftBoundary(Node* node, vector<int>& res) {
    if (!node || (!node->left && !node->right)) return;
    res.push_back(node->val);
    if (node->left) leftBoundary(node->left, res);
    else leftBoundary(node->right, res);
}

void leaves(Node* node, vector<int>& res) {
    if (!node) return;
    if (!node->left && !node->right) res.push_back(node->val);
    leaves(node->left, res);
    leaves(node->right, res);
}

void rightBoundary(Node* node, vector<int>& res) {
    if (!node || (!node->left && !node->right)) return;
    if (node->right) rightBoundary(node->right, res);
    else rightBoundary(node->left, res);
    res.push_back(node->val);
}

vector<int> boundaryTraversal(Node* root) {
    vector<int> res;
    if (!root) return res;
    res.push_back(root->val);
    leftBoundary(root->left, res);
    leaves(root->left, res);
    leaves(root->right, res);
    rightBoundary(root->right, res);
    return res;
}

int main() {
    Node* root = new Node(1);
    root->left = new Node(2);
    root->right = new Node(3);
    root->left->left = new Node(4);
    root->left->right = new Node(5);
    root->right->left = new Node(6);
    root->right->right = new Node(7);
    vector<int> res = boundaryTraversal(root);
    for (int x : res) cout << x << " ";
    return 0;
}

//Maximum Level Sum in a Binary Tree
#include <iostream>
#include <queue>
using namespace std;

struct Node {
    int val;
    Node *left, *right;
    Node(int x) : val(x), left(nullptr), right(nullptr) {}
};

int maxLevelSum(Node* root) {
    if (!root) return 0;
    queue<Node*> q;
    q.push(root);
    int maxSum = root->val;
    while (!q.empty()) {
        int levelSum = 0, size = q.size();
        for (int i = 0; i < size; i++) {
            Node* node = q.front();
            q.pop();
            levelSum += node->val;
            if (node->left) q.push(node->left);
            if (node->right) q.push(node->right);
        }
        maxSum = max(maxSum, levelSum);
    }
    return maxSum;
}

int main() {
    Node* root = new Node(1);
    root->left = new Node(2);
    root->right = new Node(3);
    root->left->left = new Node(4);
    root->left->right = new Node(5);
    root->right->right = new Node(8);
    cout << maxLevelSum(root);
    return 0;
}

#include <iostream>
#include <vector>
#include <queue>
using namespace std;

vector<vector<int>> tree;
vector<int> dist;

void bfs(int start, int &farthest) {
    queue<int> q;
    q.push(start);
    dist[start] = 0;
    while (!q.empty()) {
        int node = q.front();
        q.pop();
        for (int neighbor : tree[node]) {
            if (dist[neighbor] == -1) {
                dist[neighbor] = dist[node] + 1;
                q.push(neighbor);
                if (dist[neighbor] > dist[farthest]) farthest = neighbor;
            }
        }
    }
}

int longestPath(int n) {
    dist.assign(n + 1, -1);
    int farthest = 1;
    bfs(1, farthest);
    dist.assign(n + 1, -1);
    bfs(farthest, farthest);
    return dist[farthest];
}

int main() {
    int n, u, v;
    cin >> n;
    tree.assign(n + 1, vector<int>());
    for (int i = 0; i < n - 1; i++) {
        cin >> u >> v;
        tree[u].push_back(v);
        tree[v].push_back(u);
    }
    cout << longestPath(n);
    return 0;
}