#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream in("darb.in");
ofstream out("darb.out");

const int Nmax = 100005;

int x;
vector<int> A[Nmax];

void BFS (int S, vector<int>&viz, queue<int>&Q)
{
    viz[S] = 1;
    Q.push(S);

    while (!Q.empty())
    {
        x = Q.front();
        Q.pop();

        for (int i = 0; i < A[x].size(); i++)
        {
            if (!viz[A[x][i]])
            {
                Q.push(A[x][i]);
                viz[A[x][i]] = viz[x] + 1;
            }
        }
    }
}

int main()
{
    int n;
    queue<int> Q;
    vector<int> viz(Nmax);

    in >> n;

    for (int i = 1; i < n; i++)
    {
        int x, y;
        in >> x >> y;

        A[x].push_back(y);
        A[y].push_back(x);
    }

    BFS(1, viz, Q);

    for (int i = 1; i <= n; i++)
        viz[i] = 0;

    BFS(x, viz, Q);

    out << viz[x];
}