#include <cstdio>
#include <vector>
#define N 100002
#include <deque>
#define INF 2000000000

using namespace std;
FILE* f, * g;

vector <int> graph[N];
deque <int> q;
int last, dist[N];

void bf(int nod)
{
    q.push_back(nod);
    dist[nod] = 0;
    while (!q.empty())
    {
        nod = q.front();
        q.pop_front();
        for (int i = 0;i < graph[nod].size();++i)
            if (dist[graph[nod][i]] > dist[nod] + 1)
            {
                dist[graph[nod][i]] = dist[nod] + 1;
                last = graph[nod][i];
                q.push_back(last);
            }
    }
}
int main()
{
    f = fopen("darb.in", "r");
    g = fopen("darb.out", "w");
    int n, x, y;
    fscanf(f, "%d", &n);
    for (int i = 1;i <= n;++i)
    {
        fscanf(f, "%d %d", &x, &y);
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    for (int i = 1;i <= n;++i)
        dist[i] = INF;
    bf(1);
    for (int i = 1;i <= n;++i)
        dist[i] = INF;
    bf(last);
    fprintf(g, "%d\n", dist[last] + 1);
    fclose(f);
    fclose(g);
    return 0;
}