#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <map>
#include <cmath>
using namespace std;
ifstream in("darb.in");
ofstream out("darb.out");
int main()
{
    int n,m,i,x,y,u,dm,p;
    in>>n;
    vector <int> v[n+1];
    queue <int> q;
    int h[n+1];
    int d[n+1];
    for(i=0;i<n;i++)
    {
        in>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for(i=1;i<=n;i++)
    {
        d[i]=0;
        h[i]=0;
    }
    q.push(1);
    while(!q.empty())
    {
        u = q.front();
        h[u]=1;
        q.pop();
        for(auto it2 = v[u].begin();it2!=v[u].end();++it2)
            if (h[*it2]==0)
            {
                q.push(*it2);
                h[*it2] = 1;
                d[*it2] = d[u]+1;
            }
    }
    dm = 0;
    p = 0;
    for(i=1;i<=n;i++)
        if (d[i]>dm)
        {
            dm = d[i];
            p = i;
        }
    q.push(p);
    for(i=1;i<=n;i++)
    {
        d[i]=0;
        h[i]=0;
    }
    while(!q.empty())
    {
        u = q.front();
        h[u]=1;
        q.pop();
        for(auto it2 = v[u].begin();it2!=v[u].end();++it2)
            if (h[*it2]==0)
            {
                q.push(*it2);
                h[*it2] = 1;
                d[*it2] = d[u]+1;
            }
    }
    for(i=1;i<=n;i++)
        if (d[i]>dm)
            dm = d[i];
    out<<(dm+1);
    return 0;
}