#include <cstdio>
#include <vector>
#include <queue>
#include <cstring>
using namespace std;
vector <int> v[100005];
queue <int> q;
bool viz[100005];
int last,sol,ad[100005];
int bfs(int start)
{
    memset(ad,0,100001);
    memset(viz,0,100001);
    int x;
    q.push(start);
    ad[start]=1;
    viz[start]=1;
    while(!q.empty())
    {
        x=q.front();
        for(int i=1;i<=v[x][0];i++)
            if(!viz[v[x][i]])
            {
                ad[v[x][i]]=ad[x]+1;
                viz[v[x][i]]=1;
                q.push(v[x][i]);

                last=v[x][i];
                sol=ad[v[x][i]];
            }
        q.pop();
    }
}
int main()
{
    freopen("darb.in","r",stdin);
    freopen("darb.out","w",stdout);

    int a,b,n;
    scanf("%d",&n);

    for(int i=1;i<=n;i++) v[i].push_back(0);

    while(scanf("%d%d",&a,&b)!=EOF)
    {
        v[a][0]++;v[b][0]++;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    bfs(1);
    bfs(last);
    printf("%d",sol);


    return 0;
}