#include <cstdio>
#include <vector>
#define N 100010

using namespace std;

int n, i, j, x, y, dist[N], viz[N];
vector<int> v[N];
void df(int);

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

    scanf("%d", &n);

    for(i = 1; i < n; i++)
    {
        scanf("%d%d", &x, &y);
        v[x].push_back(y);
        v[y].push_back(x);
    }

    df(1);

    for(i = 1, j = 1; i <= n; i++)
        if(dist[i] > dist[j])
            j = i;

    for(i = 1; i <= n; i++)
    {
        viz[i] = 0;
        dist[i] = 0;
    }

    df(j);

    for(i = 1, j = 1; i <= n; i++)
        if(dist[i] > dist[j])
            j = i;

    printf("%d\n", dist[j] + 1);

    return 0;
}
void df(int nod)
{
    viz[nod] = 1;
    for(auto vec:v[nod])
        if(!viz[vec])
        {
            dist[vec] = dist[nod] + 1;
            df(vec);
        }
}