#include <bits/stdc++.h>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
int n, viz[100005], d[100005];
vector<int>L[100005];

void BFS(int x)
{
    int k;
    queue<int> q;
    q.push(x); viz[x] = 1; d[x] = 0;
    while(!q.empty())
    {
        k = q.front();
        q.pop();
        for(int i : L[k])
            if(!viz[i])
        {
            q.push(i);
            d[i] = d[k] + 1;
            viz[i] = 1;
        }
    }
}

int main()
{
    int i, j, m = 0, x = 0;
    fin >> n;
    while(fin >> i >> j)
    {
        L[i].push_back(j);
        L[j].push_back(i);
    }
    BFS(1);
    for(i = 1; i <= n; i++)
        if(m < d[i])
    {
        m = d[i];
        x = i;
    }
    for(i = 1; i <= n; i++)
        viz[i] = d[i] = 0;
    BFS(x);
    m = 0;
    for(i = 1; i <= n; i++)
        if(m < d[i]) m = d[i];
    fout << 1 + m << "\n";
    return 0;
}