#include<cstdio>
#include<vector>
#include<deque>
#include<bitset>
using namespace std;
const int NMAX = 100005;
const int INF = 1<<30;
int N,i,X,Y,D[NMAX],M,Node;
vector<int> V[NMAX];
deque<int> Q;
bitset<NMAX> viz;
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);
	}
	Q.push_back(1); D[1]=1; viz[1]=1;
	while(!Q.empty())
	{
	    X=Q.front(); Q.pop_front();
	    for(vector<int>::iterator it=V[X].begin();it!=V[X].end();it++)
            if(!viz[*it])
            {
                viz[*it]=1;
                D[*it]=D[X]+1;
                Q.push_back(*it);
            }
	}
	for(i=1;i<=N;i++) if(D[i]>M) {M=D[i]; Node=i;}
	for(i=1;i<=N;i++) D[i]=INF; D[Node]=1;
	viz=0; Q.push_back(Node); viz[Node]=1;
	while(!Q.empty())
	{
	    X=Q.front(); Q.pop_front();
	    for(vector<int>::iterator it=V[X].begin();it!=V[X].end();it++)
            if(!viz[*it])
            {
                viz[*it]=1;
                D[*it]=D[X]+1;
                Q.push_back(*it);
            }
	}
	for(i=1;i<=N;i++) M=max(M,D[i]);
	printf("%d\n",M);
	return 0;
}