#include <fstream>
#include <cstdio>
#include <vector>
#include <cstring>
#define Nmax 100001
using namespace std;

ofstream g("darb.out");

int n,sav,mx,x,y;
bool uz[Nmax];
vector<int> V[Nmax];

void dfs(int nod, int nr)
{
    uz[nod] = 1;
    if (nr>mx)
    {
        mx = nr;
        sav = nod;
    }
    for (int i=0;i<V[nod].size();i++)
    {
        if (!uz[V[nod][i]])
            dfs(V[nod][i],nr+1);
    }
}
int main()
{
    freopen("darb.in","r",stdin);
    scanf("%d",&n);
    for (int i=1;i<=n;i++)
    {
        scanf("%d%d",&x,&y);
        V[x].push_back(y);
        V[y].push_back(x);
    }

    dfs(1,1);

    memset(uz,0,sizeof(uz));

    dfs(sav,1);

    g<<mx;
    return 0;
}