#include<bits/stdc++.h>
using namespace std;

#define ll long long
const int mod = 1e9+7;
const int maxn = 1e6+10;

namespace IO{
	void openfile(){
		#ifndef ONLINE_JUDGE
		freopen("in.in","r",stdin);
		freopen("out.out","w",stdout);
		#endif
	}

	int add(int x,int y){
		x+=y;
		if(x>=mod)
			x-=mod;
		return x;
	}

	int sub(int x,int y){
		x-=y;
		if(x<0)
			x+=mod;
		return x;
	}

	inline int read(){
		int x = 0,f = 0;
		char c = getchar();
		while(!isdigit(c))
			f|=c=='-',c = getchar();
		while(isdigit(c))
			x = x*10+c-'0',c = getchar();
		if(f)x = -x;
		return x;
	}
}
using namespace IO;

int n,dep[maxn],ans,f[maxn][2];
set<int>q;
vector<int>e[maxn],d[2];

void dfs(int x,int fa){
	dep[x] = dep[fa]+1;
	for(auto v:e[x]){
		if(v==fa)
			continue;
		dfs(v,x);
	}
}

void dfs1(int x,int fa){
	if(dep[x]&1){
		auto y = q.lower_bound(x);
		if(y!=q.begin())
			y--;
		if(y!=q.begin())
			ans = max(ans,*y);
	}
	for(auto v:e[x]){
		if(v==fa)continue;
		dfs(v,x);
	}
	q.insert(x);
}

void dfs3(int x,int fa){
	f[x][dep[x]&1] = x;
	for(auto v:e[x]){
		if(v==fa)continue;
		dfs3(v,x);
		f[x][0] = max(f[v][0],f[x][0]);
		f[x][1] = max(f[x][1],f[v][1]);
	}
}

signed main(){
	openfile();
	n = read();
	for(int i=1;i<n;i++){
		int x = read(),y = read();
		e[x].push_back(y),e[y].push_back(x);
	}
	if(!(n&1)){
		printf("%d\n",n);
		return 0;
	}
	for(int i=1;i<=n;i++)
		if(e[i].size()==1)
			ans = max(ans,i);
	dfs(n,0);
	for(int i=1;i<=n;i++)
		if(!(dep[i]&1))
			ans = max(ans,i);
	dfs1(n,0);
	dfs2(n,0);
	for(auto v:e[n]){
		d[0].push_back(f[v][0]);
		d[1].push_back(f[v][1]);
	}
	sort(d[0].begin(),d[0].end());
	sort(d[1].begin(),d[1].end());
	if(e[n].size()>=3)
		ans = max(ans,max(d[0][e[n].size()-3],d[1][e[n].size()-3]));
	printf("%d\n",ans);
	return 0;
}

answer.code: In function ‘int main()’:
answer.code:100:9: error: ‘dfs2’ was not declared in this scope; did you mean ‘dfs3’?
  100 |         dfs2(n,0);
      |         ^~~~
      |         dfs3