#include <cstdio>
#include <vector>
#define N 100002
#include <deque>
#define INF 2000000000

using namespace std;
FILE *f,*g;

vector <int> graph[N];
deque <int> q;
int last,dist[N];

void bf(int nod)
{
    q.push_back(nod);
    dist[nod]=0;
    while(!q.empty())
    {
        nod=q.front();
        q.pop_front();
        for(int i=0;i<graph[nod].size();++i)
            if(dist[graph[nod][i]]>dist[nod]+1)
            {
                dist[graph[nod][i]]=dist[nod]+1;
                last=graph[nod][i];
                q.push_back(last);
            }
    }
}
int main()
{
    f=fopen("darb.in","r");
    g=fopen("darb.out","w");
    int n,x,y;
    fscanf(f,"%d",&n);
    for(int i=1;i<=n;++i)
    {
        fscanf(f,"%d %d",&x,&y);
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    for(int i=1;i<=n;++i)
        dist[i]=INF;
    bf(1);
    for(int i=1;i<=n;++i)
        dist[i]=INF;
    bf(last);
    fprintf(g,"%d\n",dist[last]+1);
    fclose(f);
    fclose(g);
    return 0;
}