#include <fstream>
#include <vector>
#include <queue>
#include <cstring>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
int N;
vector <int> G[100005];
queue <int> Q;
int Distance[100005];
bool Use[100005];
int PMax,Max;
void Read()
{
    int i;
    f>>N;
    for(i=1;i<=N-1;i++)
    {
        int x,y;
        f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
}
void FirstBFS()
{
    Q.push(1);
    Use[1]=1;
    while(!Q.empty())
    {
        int node=Q.front();
        Q.pop();
        for(unsigned int i=0;i<G[node].size();i++)
        {
            int neighbour=G[node][i];
            if(Use[neighbour]==0)
            {
                Distance[neighbour]=Distance[node]+1;
                Q.push(neighbour);
                Use[neighbour]=1;
                if(Distance[neighbour]>Max)
                {
                    Max=Distance[neighbour];
                    PMax=neighbour;
                }
            }
        }
    }
}
void SecondBFS()
{
    Q.push(PMax);
    Use[PMax]=1;
    while(!Q.empty())
    {
        int node=Q.front();
        Q.pop();
        for(unsigned int i=0;i<G[node].size();i++)
        {
            int neighbour=G[node][i];
            if(Use[neighbour]==0)
            {
                Distance[neighbour]=Distance[node]+1;
                Q.push(neighbour);
                Use[neighbour]=1;
                Max=max(Max,Distance[neighbour]);
            }
        }
    }
    g<<Max+1<<"\n";
}
int main()
{
    Read();
    FirstBFS();
    Max=0;
    memset(Distance,0,sizeof(Distance));
    memset(Use,0,sizeof(Use));
    SecondBFS();
    return 0;
}