#include <bits/stdc++.h>
#include <iostream>

using namespace std;

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


vector<int> a[100010];
queue<int> q;
int pret[100010];
int N,u,d;




void bfs(int S)
{
    memset(pret, 0, sizeof(pret));


    q.push(S);
    pret[S] = 1;


    while(!q.empty())
    {
        int x = q.front();


        for(auto i : a[x])
        {


            if(!pret[i])
            {
                q.push(i);
                pret[i] = pret[x] + 1;
                d = pret[i];
                u = i;

            }
        }

        q.pop();


    }
}


int main()
{
    int N;
    f>>N;
    int x,y;

    while(in>>x>>y)
    {
        a[x].push_back(y);
        a[y].push_back(x);


    }
    bfs(1);
    bfs(u);

    g<<d<<"\n";


    return 0;
}