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

ifstream fin ("darb.in");
ofstream fout ("darb.out");
 
class CentroidOperations {
    int n;
    vector<vector<int>> tree;
    vector<int> sub, maxSub, from, depth;
    vector<int> sol;
  public:
    void layerDfs(int x, int f) {
        from[x] = f;
        depth[x] = (f == -1 ? 0 : depth[f] + 1);

        for (auto y : tree[x]) {
            if (y == f || y == -1)
                continue;
            layerDfs(y, x);
        }
    }

    int getFarthest(int root) {
        if (from.size() < n + 1) {
            from.resize(n + 1);
            depth.resize(n + 1);
        }

        layerDfs(root, -1);

        int farthest = root;
        for (int i = 1; i <= n; ++i) {
            if (depth[i] > depth[farthest])
                farthest = i;
        }

        return farthest;
    }

    vector<int> getDiameter(int root) {
        int start = getFarthest(root);
        int end = getFarthest(start);
        
        vector<int> diameter;
        for (int i = end; i != -1; i = from[i])
            diameter.push_back(i);

        return diameter;
    }

    vector<int> getCenters(int root) {
        auto diam = getDiameter(root);
        int half = diam.size() / 2;
        if (diam.size() & 1) {
            return {diam[half]};
        } else {
            return {diam[half-1], diam[half]};
        }
    }

    void subDfs(int x, int f) {
        sub[x] = 1;

        for (auto y : tree[x]) {
            if (y == f || y == -1)
                continue;

            subDfs(y, x);
            sub[x] += sub[y];
        }
    }

    void centroidDfs(int x, int f, int n) {
        sub[x] = 1;
        maxSub[x] = 0;

        for (auto y : tree[x]) {
            if (y == f || y == -1)
                continue;

            centroidDfs(y, x, n);
            maxSub[x] = max(maxSub[x], sub[y]);
            sub[x] += sub[y];
        }

        maxSub[x] = max(maxSub[x], n - sub[x]);

        if (sol.empty() || maxSub[sol[0]] > maxSub[x]) {
            sol = {x};
        } else if (maxSub[sol[0]] == maxSub[x]) {
            sol.push_back(x);
        }
    }

    vector<int> getCentroids(int root, int n) {
        if (sub.size() < this->n+1) {
            sub.resize(this->n+1);
            maxSub.resize(this->n+1);
        }
        sol = {};

        centroidDfs(root, 0, n);

        return sol;
    }

    bool centroidDecomposition(int root, int father, int n) {
        int rememberPos = -1;
        for (int i = 0; i < tree[root].size(); ++i) {
            if (tree[root][i] == father) {
                tree[root][i] = -1;
                rememberPos = i;
            }
        }

        auto centroids = getCentroids(root, n);

        bool good = false;

        for (auto centroid : centroids) {
            bool ok = (father == -1 || root == centroid);
            if (!ok)
                continue;

            for (auto son : tree[centroid]) {
                if (son != -1) {
                    subDfs(son, centroid);
                    ok &= centroidDecomposition(son, centroid, sub[son]);
                    if (!ok)
                        break;
                }
            }

            good |= ok;
        }

        if (rememberPos != -1)
            tree[root][rememberPos] = father;
        return good;
    }

    CentroidOperations (const vector<vector<int>>& tree) : tree(tree) {
        n = tree.size() - 1;
    }
};
 
int main() {
    int n;
    fin >> n;

    vector<vector<int>> tree(n+1);

    for (int i = 1; i < n; ++i) {
        int a, b;
        fin >> a >> b;
        tree[a].push_back(b);
        tree[b].push_back(a);
    }

    CentroidOperations cop(tree);
    cout << cop.getDiameter(1).size();
}