#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
const int NMAX = 100001;
int n, dis[NMAX], maxi, indmaxi;
bool viz[NMAX];
vector<int> G[NMAX];
void BFS(int x)
{
    queue<int> Q;
    Q.push(x);
    viz[x] = dis[x] = 1;
    while(!Q.empty())
    {
        int crt = Q.front();
        Q.pop();
        for(const int &i : G[crt])
            if(!viz[i])
            {
                Q.push(i);
                viz[i] = 1;
                dis[i] = dis[crt] + 1;
            }
    }
}
int main()
{
    int x, y, i;
    f >> n;
    for(i = 1; i < n; i++)
    {
        f >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    BFS(1);
    for(i = 1; i <= n; i++)
        if(dis[i] > maxi)
        {
            maxi = dis[i];
            indmaxi = i;
        }
    for(i = 1; i <= n; i++)
        viz[i] = dis[i] = 0;
    BFS(indmaxi);
    maxi = -1;
    for(i = 1; i <= n; i++)
        if(dis[i] > maxi) maxi = dis[i];
    g << maxi;
    f.close();
    g.close();
    return 0;
}