#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

ifstream in("darb.in");
ofstream out("darb.out");

int n;
vector<int> arbore[100005];
bool marcaj[100005];
int nod1;
bool ok;
int diametru;

void DFS(int nod)
{
    marcaj[nod]=1;
    for(int i=0;i<arbore[nod].size();i++)
    {
        if(!(marcaj[arbore[nod][i]]))
        {
            if(ok==1)
                diametru++;
            nod1=arbore[nod][i];
            DFS(arbore[nod][i]);
        }
    }
    ok=1;
}

int main()
{
    int x,y;
    in>>n;
    while(in>>x>>y)
    {
        arbore[x].push_back(y);
    }
    DFS(1);
    DFS(nod1);
    out<<diametru+1;
    return 0;
}