#include <fstream>
#include <queue>
#include <vector>
 
#define NMax 100010
 
using namespace std;
 
ifstream f("darb.in");
ofstream g("darb.out");
 
int nodes, dist[NMax], leaf, Max = -1;
bool mark[NMax];
queue<int> Q;
vector<int> G[NMax];
 
void BFS(int node)
{
    Q.push(node);
 
    for (int i = 1; i <= nodes; i++) {
        dist[i] = 0;
        mark[i] = false;
    }
 
    mark[node] = true;
 
    while (!Q.empty()) {
         
        int crtNode = Q.front();
        Q.pop();
 
        for (vector<int>::iterator it = G[crtNode].begin(); it != G[crtNode].end(); it++) {
            if (!mark[*it]) {
                Q.push(*it);
                mark[*it] = true;
 
                dist[*it] = dist[crtNode] + 1;
 
                Max = dist[*it];
                leaf = *it;
            }
        }
 
    }
}
 
int main()
{
    f >> nodes;
 
    int n1, n2;
    for (int i = 1; i <= nodes; i++) {
        f >> n1 >> n2;
 
        G[n1].push_back(n2);
        G[n2].push_back(n1);
    }
 
    BFS(1);
    BFS(leaf);
 
    g << Max + 1;
 
    return 0;
}