#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
int n;
int d[100001],viz[100001];
vector <int> V[100001];
queue <int> C;
int maxi,r,maxi1;
void bfs(int x)
{   int v,i;
    d[x]=1;
    viz[x]=1;
    vector <int> :: iterator it;
    C.push(x);
    while(!C.empty())
    {
        v=C.front();
        C.pop();
        for(it=V[v].begin();it!=V[v].end();it++)
            if(viz[*it]==0)
            {
                d[*it]=d[v]+1;
                viz[*it]=1;
                C.push(*it);
            }
    }
    for(i=1;i<=n;i++)
        if(d[i]>maxi)
        {
        maxi=d[i];
        r=i;
        }
    for(i=1;i<=n;i++)
        d[i]=viz[i]=0;
    d[r]=1;
    C.push(r);
    while(!C.empty())
    {
        v=C.front();
        C.pop();
        for(it=V[v].begin();it!=V[v].end();it++)
            if(viz[*it]==0)
            {
                d[*it]=d[v]+1;
                viz[*it]=1;
                C.push(*it);
            }
    }
    for(i=1;i<=n;i++)
        if(d[i]>maxi1)
            maxi1=d[i];
    fout<<maxi1;

}
int main()
{
    int i,x,y;
fin>>n;
for(i=1;i<=n;i++)
{
    fin>>x>>y;
    V[x].push_back(y);
    V[y].push_back(x);
}
bfs(1);
    return 0;
}