#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define inf 10000000
using namespace std;
ifstream in("darb.in");
ofstream out("darb.out");
queue <int> q;
vector <int> v[100003];
void bfs(int nod,int d[],int n)
{
    int visited[ n+1],u;
    for(int i = 1 ; i <= n ; i ++)
    {
        d[i]=inf;
        visited[i] = false;
    }
    d[nod] = 0;
    q.push(nod);
    while(!q.empty())
    {
        u = q.front();
        visited[u]=1;
        q.pop();
        for(auto it2 = v[u].cbegin();it2!=v[u].cend();++it2)
            if (visited[*it2]==0)
            {
                q.push(*it2);
                visited[*it2] = 1;
                d[*it2] = d[u]+1;
            }
    }
}
int main()
{
    int n,i,x,y,dm,p;
    in >> n;
    int d[n+1];
    for( i = 0 ; i < n ; i ++)
    {
        in >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    dm = 0;
    p = 0;
    bfs(1,d,n);
    for( i = 1 ; i <= n ; i ++)
        if (d[i]>dm)
        {
            dm = d[i];
            p = i;
        }
    bfs(p,d,n);
    for( i = 1 ; i <= n ; i ++)
        if (d[i]>dm)
            dm = d[i];
    out<<(dm+1);
    return 0;
}