#include <cstdio>
#include <vector>
#include <queue>

#define pb push_back

using namespace std;

vector <int> v[100010];
queue <int> q;

int n, a[100010], ultim;

inline void parcurgere (int x)
{
    for (int i = 1; i <= n; ++i)
        a[i] = 0;

    q.push (x);
    a[x] = 1;

    while (!q.empty ())
    {
        int y = q.front ();
        for (int i = 0; i < v[y].size (); ++i)
            if (!a[v[y][i]])
            {
                q.push (v[y][i]);
                a[v[y][i]] = a[y] + 1;
                ultim = v[y][i];
            }

        q.pop ();
    }
}

int main ()
{
    freopen ("darb.in", "r", stdin);
    freopen ("darb.out", "w", stdout);

    scanf ("%d", &n);

    for (int i = 1; i <= n; ++i)
    {
        int x, y;
        scanf ("%d %d", &x, &y);

        v[x].pb (y);
        v[y].pb (x);
    }

    parcurgere (1);
    parcurgere (ultim);

    printf ("%d\n", a[ultim]);

    return 0;
}