#include <fstream>
#include <vector>
#include <cstring>

using namespace std;

ifstream fin("darb.in");
ofstream fout("darb.out");

vector<int> a[100001];
int f[100001];
int rez,pred,maxx,nmaxx;

void dfs(int i)
{
    f[i]=f[pred]+1;
    if(f[i]>maxx)
    {
        maxx=f[i];
        nmaxx=i;
    }
    for(auto y:a[i])
    {
        if(!f[y])
            {
                pred=i;
                dfs(y);
            }
    }
}

int main()
{
    int n;
    fin>>n;
    int x,y;
    while(fin>>x>>y)
    {
        a[x].push_back(y);
        a[y].push_back(x);
    }
    dfs(1);
    memset(f, 0, sizeof(f));
    maxx=0;
    dfs(nmaxx);
    fout<<maxx;
    return 0;
}