#include <cstdio>
#include <vector>
#include <queue>
#include <iostream>
#define nmax 100005
using namespace std;

FILE *f=fopen("darb.in","r");
FILE *g=fopen("darb.out","w");

vector<int>Q[nmax],lastlvl;
queue<int>que;

int n,cost[nmax],diam;
bool viz[nmax];

void read()
{
    fscanf(f,"%d",&n);
    for (int i=1; i<n; ++i)
    {
        int a,b;
        fscanf(f,"%d %d",&a,&b);
        Q[a].push_back(b);
    }
}

void dfs(int nod)
{
    viz[nod]=true;
    int mx1=0,mx2=0;
    for (auto w:Q[nod])
    {
        if (!viz[w])
        {
            dfs(w);
            cost[nod]=max(cost[nod],cost[w]+1);
            if (cost[w]+1>=mx1)
            {
                mx2=mx1;
                mx1=cost[w]+1;
            }
            else if (cost[w]+1>mx2)
                mx2=cost[w]+1;
        }
    }
    diam=max(diam,mx1+mx2+1);
}

void solve()
{
    dfs(1);
    fprintf(g,"%d",diam);
}

int main()
{
    read();
    solve();
    return 0;
}