#include <bits/stdc++.h>

using namespace std;

int n,sol[100003];
vector<int> a[100003];
queue<int> q;

inline void Citire()
{
    int i,x,y;
    ifstream fin("darb.in");
    fin>>n;
    for(i=1;i<=n;i++)
    {
        fin>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    fin.close();
}

inline void BFS(int s)
{
    int i,j;
    unsigned int k;
    for(i=1;i<=n;i++)
        sol[i]=-1;
    sol[s]=0;
    q.push(s);
    while(!q.empty())
    {
        i=q.front();
        q.pop();
        for(k=0;k<a[i].size();k++)
        {
            j=a[i][k];
            if(sol[j]==-1)
            {
                sol[j]=1+sol[i];
                q.push(j);
            }
        }
    }
}



int main()
{
    int mx,nod,i;
    Citire();
    BFS(1);
    mx=0;
    for(i=1;i<=n;i++)
        if(sol[i]>mx)
        {
            mx=sol[i];
            nod=i;
        }
    BFS(nod);
    mx=0;
    for(i=1;i<=n;i++)
        mx=max(mx,sol[i]);

    ofstream fout("darb.out");
    fout<<mx+1<<"\n";
    fout.close();
    return 0;
}