#include <bits/stdc++.h>

using namespace std;

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

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

void dfs(int nod)
{
    v[nod]=1;
    for(int i=0;i<a[nod].size();i++)
        if(v[a[nod][i]]==0)
        {
            int x=a[nod][i];
            dist[x]=dist[nod]+1;
            if(dist[x]>Max)
                Max=dist[x], p=x;
            dfs(x);
        }
}
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;
    }

    memset(v,0,sizeof(v));
    dist[1]=0;
    dfs(1);

    for(int i=1;i<=N;i++)
    {
        dist[i]=INT_MAX;
        v[i]=0;
    }

    dist[p]=0;
    dfs(p);

    fout << Max+1;

	return 0;
}