#include<fstream>
#include<vector>
#include<deque>
#include<cstring>
using namespace std;
vector <int> L[100002];
deque <int> q;
int n, i, x, y, last, d[100002], nod, fiu, darb;
void bfs()
{
    while(!q.empty())
    {
        nod=*q.begin();
        for(int i=0; i<L[nod].size(); i++)
        {
            int fiu=L[nod][i];
            if(d[fiu]==0)
            {
                d[fiu]=d[nod]+1;
                q.push_back(fiu);
                last=fiu;
                darb=d[fiu];
            }
        }
        q.pop_front();
    }
}
ifstream in("darb.in");
ofstream out("darb.out");
int main()
{
    in>>n;
    for(i=1; i<n; i++)
    {
        in>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
    q.push_back(1);
    d[1]=1;
    bfs();
    memset(d, 0, sizeof(d));
    q.push_back(last);
    d[last]=1;
    bfs();
    out<<darb;
    return 0;
}