#include <fstream>
#include <vector>
#include <cstring>
#include <queue>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");

int N, x, y, D[100005], sol, prec;
vector < int > G[100005];
queue < int > Q;

void bfs(int sursa)
{
    memset(D, -1, sizeof(D));
    D[sursa]=1; Q.push(sursa);

    while (!Q.empty())
    {
        int nod=Q.front(); Q.pop();
        vector < int >::iterator it=G[nod].begin();
        for (; it!=G[nod].end(); ++it)
            if (D[*it]==-1)
            {
                D[*it]=sol=D[nod]+1;
                prec=*it; Q.push(*it);
            }
    }
}

int main()
{
    f>>N;
    for (int i=1; i<N; ++i)
    {
        f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }

    bfs(1);
    bfs(prec);

    g<<sol<<'\n';
    return 0;
}