#include <iostream>
#include <fstream>
#include <vector>
#include <bitset>
#include <map>
#include <queue>
//http://www.infoarena.ro/problema/darb
using namespace std;
#define MAX 100020
int d[MAX];
int n,m,s;
ifstream in("darb.in");
ofstream out("darb.out");
bitset <MAX> viz;
vector <int> v[MAX];
vector <int> ::iterator it;
queue <int> Q;
int main()
{   int k=0;
    int i,x,y,m=-1,m2=-1,ind=1;
    in>>n;
    for(i=1;i<=n-1;i++)
    {
        in>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    Q.push(1);
    d[1]=1;
    while(!Q.empty())
    {   x=Q.front();
        Q.pop();
        for(it=v[x].begin();it!=v[x].end();++it)
            {if(d[*it]==0||d[*it]>d[x]+1) {
                    d[*it]=d[x]+1;
                Q.push(*it);}}
    }
    for(i=1;i<=n;i++)
        if(d[i]>m){m=d[i];ind=i;}
   for(i=1;i<=n;i++)
        d[i]=0;
    Q.push(ind);
    d[ind]=1;
    while(!Q.empty())
    {   x=Q.front();
        Q.pop();
        for(it=v[x].begin();it!=v[x].end();++it)
            {if(d[*it]==0||d[*it]>d[x]+1) {
                    d[*it]=d[x]+1;
                Q.push(*it);}}
    }

    for(i=1;i<=n;i++)
        if(d[i]>m2)m2=d[i];
   out<<m2;



    return 0;
}