#include<bits/stdc++.h>
using namespace std;
int vertex;
list<int > v[10002];
int vis[10002];
int len[10003];
void read()
{
    cin>>vertex;
    for(int i=1;i<vertex;i++)
    {
        int x,y;
        cin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
}

int dfs(int x,int val=0)
{
    vis[x]=true;
    int ans=0,ans1=0;
    for(auto it=v[x].begin();it!=v[x].end();it++)
    {
        if(!vis[*it])
        {
            int x=dfs(*it,val+1);
            if(x>ans)
            {
                ans1=ans;
                ans=x;
            }
            else if(x>ans1)
                ans1=x;
        }
    }
    len[x]=ans+ans1;
    return ans+1;
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    //freopen("input.txt","r",stdin);
    read();
    dfs(1);
    cout<<*max_element(len,len+vertex+1)<<endl;
    return 0;
}