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

using namespace std;
ifstream in("darb.in");
ofstream out("darb.out");
const int N=100005;
vector<int>a[N];
queue<int>q;
bool viz[N];
int n,last,diametru,d[N];

void bfs(int x)
{
    int y;
    q.push(x);
    viz[x]=true;
    d[x]=1;
    while(!q.empty())
    {
        x=q.front();
        q.pop();
        for(unsigned i=0;i<a[x].size();i++)
        {
            y=a[x][i];
            if(!viz[y])
            {
                viz[y]=true;
                last=y;
                q.push(y);
                d[y]=1+d[x];
                diametru=d[y];
            }
        }
    }
}

int main()
{
    int x,y;
    in>>n;
    for(int i=1;i<n;i++)
    {
        in>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    bfs(1);
    for(int i=1;i<=n;i++)
    {
        d[i]=0;
        viz[i]=false;
    }
    bfs(last);
    out<<diametru;
    return 0;
}