#include <fstream>
#include <vector>

using namespace std;

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

const int NMAX=1e5+5;
int n;
vector<int> adj[NMAX];

pair<int, int> DFS(int u, int pu)
{
    pair<int, int> maxv={0, u};
    for(auto v:adj[u])
    {
        if(v==pu)
            continue;
        maxv=max(maxv, DFS(v, u));
    }
    maxv.first++;
    return maxv;
}

int main()
{
    in>>n;
    for(int i=1;i<n;i++)
    {
        int a, b; in>>a>>b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    out<<DFS(DFS(1, 0).second, 0).first;
    return 0;
}