#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

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

const int NMAX = 100005;
int n, nivm, poz;
int viz[NMAX];
vector<int>G[NMAX];

void DFS(int Nod, int niv) {
    viz[Nod]=1;
    if(niv>nivm) {
        nivm=niv;
        poz=Nod;
    }
    for(unsigned i=0; i<G[Nod].size(); ++i) {
        int v=G[Nod][i];
        if(!viz[v])
            DFS(v, niv+1);
    }
}

int main() {
    int x,y;
    fin>>n;
    for(int i=1; i<=n; ++i) {
        fin>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    DFS(1,0);
    for(int i=1; i<=n; ++i)
        viz[i]=0;
    DFS(poz, 0);
    fout<<nivm+1;
    return 0;
}