# include <cstdio>
# include <vector>
using namespace std;
FILE *f=freopen("darb.in","r",stdin);
FILE *g=freopen("darb.out","w",stdout);

const int NMAX= 100001;
vector <int> G[NMAX];
int n;
void read()
{
    scanf("%d",&n);
    for (int i=1;i<=n;i++)
    {
        int x,y;
        scanf("%d %d",&x,&y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
}
int maxim=0,c1;
bool viz[NMAX];
void dfs1(int node, int dist)
{
    viz[node]=true;
    for (vector <int> :: iterator it=G[node].begin();it!=G[node].end();it++)
    {
        if (dist>maxim)
        {
            maxim=dist;
            c1=node;
        }
        if (!viz[*it]) dfs1(*it,dist+1);
    }
}
void dfs2(int node, int dist)
{
    viz[node]=true;
    for (vector <int> :: iterator it=G[node].begin();it!=G[node].end();it++)
    {
        if (dist>maxim)
        {
            maxim=dist;
        }
        if (!viz[*it]) dfs1(*it,dist+1);
    }
}
int main()
{
    read();
    dfs1(1,0);
    maxim=0;
    for (int i=0;i<NMAX;i++) viz[i]=false;
    dfs2(c1,0);
    printf("%d\n",maxim+1);
    return 0;
}