#include <iostream>
#include <fstream>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
 
struct nod
{
    int info;
    nod* urm;
}*pt[100005];
int n,d,niv[100005];
 
void InserareNod(nod* &p,int val)
{
    nod* cap = new nod;
    cap->info = val;
    cap->urm = p;
    p = cap;
}
 
int BF(int xp)
{
    int y,p,u,C[n+1];
    p = u = 1;
    C[1] = xp;
    niv[xp] = 1;
 
    while( p <= u )
    {
        nod* cap = pt[C[p]];
 
        while( cap != NULL )
        {
            y = cap->info;
 
            if( niv[y] == 0 )
            {
                u++;
                C[u] = y;
                niv[y] = niv[C[p]] + 1;
            }
 
            cap = cap->urm;
        }
        p++;
    }
 
    return C[n];
}
 
int main()
{
    int a,b,xp;
    f>>n;
    for(int i = 1 ; i <= n ; i++)
        pt[i] = NULL;
 
    for(int i = 1 ; i < n ; i++)
    {
        f>>a>>b;
        InserareNod(pt[a],b);
        InserareNod(pt[b],a);
    }
 
    xp = BF(1);
 
    for(int i = 1 ; i <= n ; i++)
        niv[i] = 0;
 
    xp = BF(xp);
    g<<niv[xp];
 
    return 0;
}