#include <iostream>
#include <fstream>
#include <string.h>
#include <vector>
#include <queue>

using namespace std;

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

const int MAXN = 1000001;

int n,last,diam;
int counter[MAXN],IsinQ[MAXN];

vector<int> Node[MAXN];
queue<int> Q;

void BFS(int start)
{

    memset(counter,0,sizeof(counter));
    memset(IsinQ,0,sizeof(IsinQ));

    Q.push(start);
    counter[start]=1;

    IsinQ[start]=1;

    while(!Q.empty())
    {
        int x=Q.front();
        for(auto nod : Node[x])
        {
            if(IsinQ[nod]==0)
            {
                Q.push(nod);
                counter[nod]=counter[x]+1;
                IsinQ[nod]=1;

                diam=counter[nod];
                last=nod;
            }
        }

         Q.pop();
    }
}
int main()
{

    int x,y;
    in>>n;
    for(int i=0; i<n-1; i++)
    {
        in>>x>>y;
        Node[x].push_back(y);
        Node[y].push_back(x);
    }
   BFS(1);
   BFS(last);

   out<<diam;

   return 0;
}