#include <fstream>
#include <vector>
#include <algorithm>
#define DIM 100002

using namespace std;

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

int n, t[DIM], viz[DIM], x, y;

vector <int> arb[DIM];

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

void dfs(int nod, int niv)
{
    viz[nod] = 1;
    t[nod] = niv;
    for(int i = 0; i < arb[nod].size(); ++ i)
    {
        int nodc = arb[nod][i];
        if(viz[nodc] == 0)
        {
            dfs(nodc, niv + 1);
        }
    }
}

int main()
{
    f>>n;
    for(int i = 1; i < n; ++ i)
    {
        f>>x>>y;
        arb[x].push_back(y);
        arb[y].push_back(x);
    }

    dfs(1, 1);

    sort(t + 1, t + n + 1, cmp);

    g<<t[1] + t[2] - 1;

    return 0;
}