#include <fstream>
#include <vector>
#include <queue>

using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
const int NMAX =  100000;
vector <int>G[NMAX+5];
queue <int>q;
int viz[NMAX+5];
void bfs(int nod)
{
    int i;
    viz[nod] = 1;
    q.push(nod);
    while(!q.empty())
    {
        nod = q.front();
        q.pop();
        for(i=0;i<G[nod].size(); i++)
        {
            if(viz[G[nod][i]]==0)
            {
                viz[G[nod][i]] = viz[nod] + 1;
                q.push(G[nod][i]);
            }
        }
    }
}
int main()
{
    int n, i, x, y;
    fin>>n;
    for(i=1;i<=n-1;i++)
    {
        fin>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    bfs(1);
    int dmax =0, nod_start;
    for(i=1;i<=n;i++)
    {
       if(dmax< viz[i])
       {
           dmax = viz[i];
           nod_start = i;
       }
       viz[i] = 0;
    }
    bfs(nod_start);
    dmax=0;
    for(i=1;i<=n;i++)
    {
       if(dmax<viz[i])
           dmax = viz[i];
    }
    fout<<dmax<<"\n";
    return 0;
}