#include <cstdio>
#include <vector>
using namespace std;

const int nmax=100000;
int v[nmax],n,x,y,i,j,q,k,p,cost;
bool viz[nmax];
vector <int> a[nmax];

void citire()
{
    freopen("darb.in","r",stdin);
    freopen("darb.out","w",stdout);
    scanf("%d",&n);
    for(x=1;x<=n;x++)
    {
        scanf("%d %d",&i,&j);
        a[i].push_back(j);
        a[j].push_back(i);
    }
}

int main()
{
    citire();

    v[1]=1; viz[1]=1;
    q=0; k=1; p=0;
    do
    {
        for(x=q+1;x<=q+k;x++)
        {
            for(y=0;y<a[v[x]].size();y++)
                if (!viz[a[v[x]][y]])
                    viz[a[v[x]][y]]=1,
                    ++p,
                    v[q+k+p]=a[v[x]][y];
        }
        q+=k; k=p; p=0;
    }while(k>0);

    for(x=1;x<=n;x++) viz[x]=0;

    v[1]=v[q]; viz[v[q]]=1;
    q=0; k=1; p=0;
    do
    {
        cost++;
        for(x=q+1;x<=q+k;x++)
        {
            for(y=0;y<a[v[x]].size();y++)
                if (!viz[a[v[x]][y]])
                    viz[a[v[x]][y]]=1,
                    ++p,
                    v[q+k+p]=a[v[x]][y];
        }
        q+=k; k=p; p=0;
    }while(k>0);

    printf("%d\n",cost);
    return 0;
}