#include <cstdio>
#include <vector>
#include <queue>
#include <cstring>
#include <algorithm>

#define NMAX 100005

using namespace std;

vector <int> G[NMAX];
int N, dist[NMAX];

void citire()
{
    int a, b;

    scanf("%d", &N);

    for (int i = 1; i <= N; ++i)
    {
        scanf("%d %d", &a, &b);
        G[a].push_back(b);
        G[b].push_back(a);
    }
}


void bfs(int nod)
{
    vector <int> :: iterator it;
    queue <int> q;
    int n;

    q.push(nod);
    dist[nod] = 1;

    while (q.empty() == false)
    {
        n = q.front();
        q.pop();
        for (it = G[n].begin(); it != G[n].end(); ++it)
        {
            if (dist[*it] == 0)
            {
                dist[*it] = dist[n] + 1;
                q.push(*it);
            }
        }
    }
}

int main()
{
    freopen("darb.in", "r", stdin);
    freopen("darb.out", "w", stdout);

    int nodmax, dmax = 0;

    citire();
    bfs(1);
    for (int i = 1; i <= N; ++i)
    {
        if (dmax < dist[i])
        {
            dmax = dist[i];
            nodmax = i;
        }
    }
    memset(dist, 0, sizeof(dist));
    bfs(nodmax);
    dmax = 0;
    for (int i = 1; i <= N; ++i)
        dmax = max(dmax, dist[i]);
    printf("%d", dmax);

    return 0;
}