#include <bits/stdc++.h>
using namespace std;
int n,ul,diam,a,b,grad[100010];
bool viz[100010];
vector <int> v[100010];

void bfs(int x)
{
    memset(viz,0,n+2);
    memset(grad,0,n+2);
    queue <int> q;
    q.push(x);
    viz[x]=1;
    grad[x]=1;
    while(!q.empty())
    {
        int curr=q.front();
        q.pop();
        for(int i=0;i<v[curr].size();i++)
        {
            if(!viz[v[curr][i]])
            {
                viz[v[curr][i]]=1;
                grad[v[curr][i]]=grad[curr]+1;
                diam=grad[v[curr][i]];
                ul=v[curr][i];
                q.push(v[curr][i]);
            }
        }
    }
}


int main()
{
    ifstream cin("darb.in");
    ofstream cout("darb.out");
    cin>>n;
    for(int i=0;i<n-1;i++)
    {
        cin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    bfs(1);
    bfs(ul);
    cout<<diam;
    return 0;
}