#include <fstream>
#include<vector>
#define NM 1000001
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
vector<int>G[NM];
int c[NM],viz[NM],n,p,u;
void BF(int x)
{
    int i,z,w;
    for(i=1;i<=n;i++)
        viz[i]=c[i]=0;
    viz[x]=1;
    u=p=1;
    c[u]=x;
    while(p<=u)
    {
        z=c[p];p++;
        for(i=0;i<G[z].size();i++)
        {
            w=G[z][i];
            if(viz[w]==0)
            {
                viz[w]=viz[z]+1;
                u++;
                c[u]=w;
            }
        }

    }
}
int main()
{
    int i,x,y;
    fin>>n;
    for(i=1;i<n;i++)
    {
        fin>>x>>y;
        G[y].push_back(x);
        G[x].push_back(y);
    }
    BF(1);
    x=c[u];
    BF(x);
    y=c[u];
    fout<<viz[y];
    return 0;
}