#include <bits/stdc++.h>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
const int NMAX=100005;
int n,x,y,last,ans;
vector<int>dist,graph[NMAX];
queue<int>q;
void bfs(int node)
{

    dist[node]=1;
    q.push(node);
    while(!q.empty())
    {
        node=q.front();
        q.pop();
        for(int next:graph[node])
            if(!dist[next])
            {
                dist[next]=dist[node]+1;
                q.push(next);
                if(dist[next]>ans)
                {
                    ans=dist[next];
                    last=next;
                }
            }
    }
}
int main()
{
    f>>n;
    dist.resize(n+1);
    for(int i=1;i<n;i++)
    {
        f>>x>>y;
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    bfs(1);
    fill(dist.begin(),dist.end(),0);
    bfs(last);
    g<<ans;
    return 0;
}