#include<fstream>
#include<deque>
#include<vector>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");
int n,x,y,nod,i,mx;
bool viz[100005];
vector<int>a[100005];
int d[100005];
deque<int>q;
int main()
{
    f>>n;
    while(f>>x>>y)
    {
        a[x].push_back(y);
        a[y].push_back(x);
    }
    d[1]=1;
    viz[1]=1;
    q.push_back(1);
    while(!q.empty())
    {
        nod=q.front();
        q.pop_front();
        viz[nod]=1;
        for(i=0;i<a[nod].size();i++)
          if(viz[a[nod][i]]==0)
          {
              viz[a[nod][i]]=1;
              d[a[nod][i]]=d[nod]+1;
              q.push_back(a[nod][i]);
          }
    }
    d[nod]=1;
    viz[nod]=0;
    q.push_back(nod);
    while(!q.empty())
    {
        nod=q.front();
        q.pop_front();
        viz[nod]=0;
        for(i=0;i<a[nod].size();i++)
          if(viz[a[nod][i]]==1)
          {
              viz[a[nod][i]]=0;
              d[a[nod][i]]=d[nod]+1;
              q.push_back(a[nod][i]);
          }
    }
    g<<d[nod];
    return 0;
}