#include <fstream>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");

int N, x, y, D[100005], last;
vector<int> G[100005];
queue < int > Q;

void bfs(int sursa)
{
    for (int i=1; i<=N; ++i)
        D[i]=-1;
    Q.push(sursa); D[sursa]=1;
    while (Q.size())
    {
        int nod=Q.front(); Q.pop();
        vector<int>::iterator it=G[nod].begin();
        for (; it!=G[nod].end(); ++it)
            if (D[*it]<0)
                D[*it]=D[nod]+1, Q.push(*it), last=*it;
    }
}

int main()
{
    f>>N;
    for (int i=1; i<N; ++i)
    {
        f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }

    bfs(1); bfs(last);
    g<<D[last]<<'\n';
    return 0;
}