#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define ll long long
using namespace std;
ifstream in("darb.in");
ofstream out("darb.out");
int n,cost[nmax],a,b,start,mx,dm[nmax];
vector<int> vecini[nmax];
queue<int> q;
const ll nMax = 100005;

int bfs(int x,int v[])
{
    q.push(x);
    v[x]=1;
    while(!q.empty())
    {
        start=q.front();
        mx=start;
        q.pop();
        for(int i=0;i<vecini[start].size();i++)
        {
            if(!v[vecini[start][i]])
            {
                v[vecini[start][i]]=v[start]+1;
                q.push(vecini[start][i]);
            }
        }
    }
}
int main() {
    int n
    in>>n;
    for(int i=1;i<=n;i++)
    {
        in>>a>>b;
        vecini[a].push(b);
        vecini[b].push(a);
    }
    bfs(1,cost);
    bfs(mx,dm);
    out<<dm[mx];
    return 0;
}