#include <fstream>
#include <vector>
#include <deque>
#include <stack>
#include <algorithm>

using namespace std;
ifstream cin("darb.in") ;
ofstream cout("darb.out") ;

int n ;

vector<int> v[100009] ;

int past[100009] ;

int main()
{

    cin >> n ;

    for(int f = 1 ; f < n ; f ++)
    {

        int a, b ;

        cin >> a >> b ;

        v[a].push_back(b) ;

        if(past[a] == 0)past[a] = past[b] + 1 ;
            else past[b] = past[a] + 1 ;

    }

    sort(past + 1, past + n + 1) ;

    cout << past[n] + past[n - 1] - 1 ;

    return 0;
}