#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;
ifstream f("darb.in");
ofstream g("darb.out");

const int Nmax = 100005;
int n, Level[Nmax];
vector <int> G[Nmax];

void DFS(int nod, int tata)
{
    for(int i = 0; i < (int)G[nod].size(); i++)
    {
        int vecin = G[nod][i];
        if(vecin == tata) continue;
        Level[vecin] = Level[nod]+1;
        DFS(vecin, nod);
    }
}

bool Crit(int a, int b)
{
    return a>b;
}

int main()
{
    f>>n;
    for(int i = 1; i <= n; i++)
    {
        int x, y;
        f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    Level[1] = 1;
    DFS(1,0);
    sort(Level+1, Level+1+n, Crit);
    g<<(Level[1] + Level[2] -1)<<'\n';
    return 0;
}