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

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

#define pb push_back

const int N = 1e5 + 5;

int n, x, y, d[N];
vector<int> ad[N];
vector<int>::iterator it;
queue<int> q;

void read(), bfs(int);

int main()
{
    read();
    bfs(1);
    for (int i = 1; i <= n; i++) d[i] = 0;
    bfs(x);
    g << d[x] + 1;
    return 0;
}

void read(){
    f >> n;
    while (f >> x >> y){
        ad[x].pb(y);
        ad[y].pb(x);
    }
}
void bfs(int nod){
    q.push(nod);
    while(!q.empty()){
        x = q.front();
        q.pop();
        for (it = ad[x].begin(); it != ad[x].end(); it++)
            if (!d[*it]){
                d[*it] = d[x] + 1;
                q.push(*it);
            }
    }
}