#include <bits/stdc++.h>
#define Dmax 100005
#define inf 0x3F3F3F3F
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
int n,viz[Dmax],dist[Dmax],diametru,last;
vector<int>G[Dmax];
queue<int> Q;

void BFS(int start)
{
     for(int i = 1; i <= n; i++)
        dist[i] = inf;
    diametru = 0;
    Q.push(start);
    viz[start] = 1;
    dist[start] = 1;
    while(!Q.empty())
    {
        int nod = Q.front();
        Q.pop();
        for(vector<int>::iterator it = G[nod].begin(); it < G[nod].end(); it++)
            if(dist[*it] > dist[nod] + 1)
        {
            dist[*it] = dist[nod] + 1;
            Q.push(*it);
            if(diametru < dist[*it])
            {
                last = *it;
                diametru = dist[*it];
            }

        }
    }


}

int main()
{
    f>>n;
    int x,y;
    while(f>>x>>y)
    {
        G[x].push_back(y);
        G[y].push_back(x);
    }

    BFS(1);

    BFS(last);

    g<<diametru;

    return 0;
}