#include<bits/stdc++.h>
using namespace std;
int N,x,y,Max,unod,diam;
bool viz[100001];
vector <int> G[100001];
void dfs(int nod,int nr){
viz[nod]=1;
if(nr>Max)Max=nr,unod=nod;
for(int i=0;i<G[nod].size();++i)
if(!viz[G[nod][i]])
dfs(G[nod][i],nr+1);
}
int main()
{
freopen("darb.in","r",stdin);
freopen("darb.out","w",stdout);
scanf("%d",&N);
while(N--){
scanf("%d%d",&x,&y);
G[x].push_back(y);
G[y].push_back(x);
}
dfs(1,1);
memset(viz,0,sizeof(viz)),Max=0;
dfs(unod,1);
printf("%d",Max);
return 0;
}