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

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

vector <int> v[100001];
bool viz[100001];
int maxx, frunza, x, y, n, i;

void dfs(int nod, int lg)
{
    if(lg > maxx)
    {
        maxx = lg;
        frunza = nod;
    }
    viz[nod] =1;
    for(vector <int> :: iterator it = v[nod].begin(); it != v[nod].end(); ++ it)
        if(!viz[*it]) dfs(*it, lg + 1);
}
int main()
{
    f >> n;
    while(f >> x >> y)
    {
        v[x].push_back(y);
        v[y].push_back(x);
    }
    dfs(1, 1);
    memset(viz, 0, sizeof(viz));
    dfs(frunza, 1);
    g << maxx;
    return 0;
}