#include <fstream>
#include <vector>
#include <cstring>
std::ifstream cin("darb.in");
std::ofstream cout("darb.out");
#define maxn 100010
inline int max(int a,int b){if(a<b)return b;return a;}
int n;
std::vector<int> g[maxn];

int viz[maxn],SOL;
void dfs(int nod,int lvl){
	viz[nod]=lvl;
	for(auto it=g[nod].begin();it!=g[nod].end();++it)
		if(!viz[*it]){
			dfs(*it,lvl+1);
			SOL=max(SOL,viz[nod]+viz[*it]);
			if(viz[nod]<viz[*it])
				viz[nod]=viz[*it];
	}
}

int main()
{
	int x,y;
	cin>>n;
	for(int i=1;i<n;i++){
		cin>>x>>y;
		g[x].push_back(y);
		g[y].push_back(x);
	}
	dfs(1,1);
	cout<<SOL;
}