#include <cstdio>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
vector <int> arbore[100003];queue <int> chestie;
int n,dist[100003],nod;
void bfs () {
	nod=chestie.front();dist[nod]=1;
	while(chestie.size()!=0) {
		nod=chestie.front();
		for(int i=0;i<(int)arbore[nod].size();++i)
			if(dist[arbore[nod][i]]==0)
				dist[arbore[nod][i]]=dist[nod]+1,chestie.push(arbore[nod][i]);
		chestie.pop();
	}
}
int main () {
	int nr1,nr2,maxi,poz;
	freopen("darb.in","r",stdin);
	freopen("darb.out","w",stdout);
	scanf("%d", &n);
	for(int i=1;i<n;++i)
		scanf("%d%d", &nr1, &nr2),arbore[nr1].push_back(nr2),arbore[nr2].push_back(nr1);
	chestie.push(1);bfs();maxi=-1;
	for(int i=1;i<=n;++i){
		if(dist[i]>maxi)
			maxi=dist[i],poz=i;
		dist[i]=0;
	}
	chestie.push(poz);bfs();maxi=-1;
	for(int i=1;i<=n;++i)
		if(dist[i]>maxi)
			maxi=dist[i];
	printf("%d", maxi);
	return 0;
}
//de ce nu poti face doar cu bfs ?;probabil e mai optim dfs pentru ca daca nu mai poti cobori ai ajuns ?