#include <fstream>
#include <queue>
#include <vector>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
#define nmax 100001
int n, x, y, d[nmax];
bool u[nmax];
queue<int> q;
vector<int> v[nmax];
void bfs(int nod) {
    q.pop();
    u[nod] = true;
    for (int i = 0; i < v[nod].size(); ++i) if (!u[v[nod][i]]) { q.push(v[nod][i]); d[v[nod][i]] = d[nod] + 1; }
    x = nod;
}
int main()
{
    f >> n;
    for (int i = 1; i < n; ++i) {
        f >> x >> y;
        v[x].push_back(y), v[y].push_back(x);
    }
    q.push(1);
    while (!q.empty()) bfs(q.front());
    q.push(x);
    for (int i = 1; i <= n; ++i) { u[i] = false; d[i] = 0; }
    while (!q.empty()) bfs(q.front());
    g << d[x] + 1 << '\n';
    return 0;
}