#include <bits/stdc++.h>

using namespace std;

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

int N,dist[100005];
vector <int> a[100005];
queue <int> q;
int Max,p;

void bfs(int nod)
{
    dist[nod]=0;
    q.push(nod);
    while(!q.empty())
    {
        int x=q.front();
        q.pop();
        for(int i=0;i<a[x].size();i++)
        {
            int y=a[x][i];
            if(dist[x]+1<dist[y])
            {
                dist[y]=dist[x]+1;
                q.push(y);
            }
            if(dist[y]!=INT_MAX and dist[y]>Max)
                Max=dist[y], p=y;
        }
    }
}
int main()
{

	fin >> N;

	for(int i=1;i<=N;i++)
    {
        int x,y;
        fin >> x >> y;
        a[x].push_back(y);
        a[y].push_back(x);
        dist[i]=INT_MAX;
    }

    bfs(1);

    for(int i=1;i<=N;i++)
        dist[i]=INT_MAX;

    bfs(p);

    fout << Max+1;

	return 0;
}