#include <bits/stdc++.h>
#define NMax 100001
using namespace std;

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

vector<int> G[NMax];
int n, x, y, L[NMax], diametru, poz, last;
bool viz[NMax];
queue<int> q;

int cmp(int x, int y)
{
    return x > y;
}

void bfs(int k)
{
    viz[k] = true;
    q.push(k);
    L[k] = 1;
    while(!q.empty())
    {
        int nod = q.front();
        for(int i = 0; i < G[nod].size(); ++i)
            if(!viz[G[nod][i]])
        {
            viz[G[nod][i]] = true;
            q.push(G[nod][i]);
            L[G[nod][i]] = L[nod] + 1;
            diametru = L[G[nod][i]];
            last = G[nod][i];
        }
        q.pop();
    }
}

int main()
{
    f >> n;
    while(f >> x >> y)
    {
        G[x].push_back(y);
        G[y].push_back(x);
    }
    bfs(1);
    memset(viz, 0, NMax);
    memset(L, 0, NMax);
    bfs(last);
    g << diametru;
    return 0;
}