#include<bits/stdc++.h>
using namespace std;
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/priority_queue.hpp>
#define heap __gnu_pbds::priority_queue

typedef long long ll;
const int N=1e5+3;
int n,ans;
vector<int>ve[N];
struct Nod{int x,op;};
bool operator <(Nod A,Nod B){return A.x!=B.x?A.x<B.x:A.op<B.op;}
heap<Nod>q[N];
void Dfs(int x,int fa)
{
	if(ve[x].size()==1&&fa){q[x].push({1,0});return;}
	for(int y:ve[x])if(y!=fa)Dfs(y,x),q[x].join(q[y]);
	if(q[x].size()==1)
	{
		Nod t=q[x].top();q[x].pop();ans=max(ans,t.x+1);
		q[x].push({1,0});q[x].push({t.x,1});return;
	}
	Nod t1=q[x].top();q[x].pop();Nod t2=q[x].top();q[x].pop();
	int v1=t1.x+t2.x,v2=t1.op|t2.op;
	if(t2.x==1&&!t2.op&&t1.op==1&&!q[x].size())v2=0;
	q[x].push({v1+1,v2});ans=max(ans,v1+1+v2);
}
int main()
{
	cin>>n;
	if(n==1){cout<<1;return 0;}
	for(int i=1,x,y;i<n;i++)cin>>x>>y,ve[x].push_back(y),ve[y].push_back(x);
	Dfs(1,0);cout<<ans;
	return 0;
}