#include <fstream>
#include <vector>

using namespace std;

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

int n, mx, mxd;
bool used[100005];
vector <int> v[100005];

int dfs(int nod, int deep)
{
    if(deep > mx)
    {
        mx = deep;
        mxd = nod;
    }

    for(auto it = v[nod].begin(); it != v[nod].end(); ++it)
    {
        if(!used[*it])
        {
            used[*it] = true;
            dfs(*it, deep + 1);
        }
    }
}

int main()
{
    cin >> n;

    for(int i = 1; i <= n; ++i)
    {
        int a, b;
        cin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }

    dfs(1, 1);

    for(int i = 1; i <= n; ++i)
        used[i] = 0;

    dfs(mxd, 1);
    cout << mx;
    return 0;
}