#include <iostream>
#include <queue>
#include <fstream>
#include <vector>
#include <bitset>
#define NMAX 1000001
using namespace std;
ifstream f ("darb.in");
ofstream g ("darb.out");
queue < int > q;
vector < int > a[NMAX], cnt(NMAX);
int diametru, ultim, n, x, y;

void BF(int nod)
{
    bitset < NMAX > b(0);
    q.push(nod);
    b[nod] = 1;
    cnt[nod] = 1;
    int x;
    while (!q.empty())
    {
        x = q.front();
        q.pop();
        for (int i = 0; i < a[x].size(); i++)
            if (!b[a[x][i]])
            {
                q.push(a[x][i]);
                b[a[x][i]] = 1;
                cnt[a[x][i]] = cnt[x] + 1;
                ultim = a[x][i];
                diametru = cnt[a[x][i]];
            }
    }
}
int main()
{
    f>>n;
    for (int i = 1; i < n; i++)
    {
        f>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    BF(1);
    BF(ultim);
    g<<diametru;
    return 0;
}