#include <bits/stdc++.h>
#define NMAX 100001
using namespace std;

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

int viz1[NMAX], viz2[NMAX], viz3[NMAX];
list<int> *l;

int main()
{
    int n, m;
    in >> n; m = n-1;

    l = new list<int>[n+1];

    while(m--)
    {
        int x, y;
        in >> x >> y;

        l[x].push_back(y);
        l[y].push_back(x);
    }

    int nod1;
    queue<int> q1;
    q1.push(1);
    while(!q1.empty())
    {
        nod1 = q1.front(); q1.pop();
        viz1[nod1] = 1;
        for(auto it = l[nod1].begin(); it != l[nod1].end(); it++)
            if(viz1[*it] == 0)
            {
                viz1[*it] = 1;
                q1.push(*it);
            }
    }

    int nod2;
    queue<int> q2;
    q2.push(nod1);
    while(!q2.empty())
    {
        nod2 = q2.front(); q2.pop();
        viz2[nod2] = 1;

        for(auto it = l[nod2].begin(); it != l[nod2].end(); it++)
            if(viz2[*it] == 0)
            {
                viz2[*it] = 1;
                q2.push(*it);
            }
    }

    int diam = 0;
    queue<int> q3;
    q3.push(nod2);
    while(!q3.empty())
    {
        int nod3 = q3.front(); q3.pop();

        if(nod3 == nod1) break;

        for(auto it = l[nod3].begin(); it != l[nod3].end(); it++)
            if(viz3[*it] == 0)
            {
                viz3[*it] = viz3[nod3]+1;
                q3.push(*it);
            }
    }

    out << viz3[nod1]+1;

    return 0;
}