#include <bits/stdc++.h>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");

int diametru,capat,n,dist[100005];
bool use[100005];
void bfs (int k);
vector<int>M[100005];
queue<int>Q;

int main()
{
    int i,x,y;
    fin>>n;
    for (i=1; i<=n; i++)
    {
        fin>>x>>y;
        M[x].push_back(y);
        M[y].push_back(x);
    }
    bfs(1);
    bfs(capat);
    fout<<diametru+1;
    return 0;
}

void bfs (int k)
{
    int x,i;
    Q.push(k);
    while(!Q.empty())
        {
         x=Q.front();
         Q.pop();
         for(i=0; i<M[x].size(); i++)
            if (!use[M[x][i]])
                {
                  use[M[x][i]]=1;
                  Q.push(M[x][i]);
                  dist[M[x][i]]=dist[x]+1;

                  diametru=dist[M[x][i]];
                  capat=M[x][i];
                }
        }
    for (i=1; i<=n; i++)
        {
         use[i]=0;
         dist[i]=0;
        }
}