#include <fstream>
#include <queue>

using namespace std;

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

vector<int> G[100005];
int n, cnt[100005], d, ult;
bool v[100005];

void bfs(int nod) {
    queue<int> Q;
    for(int i = 1; i <= n; i++) {
        cnt[i] = 0;
        v[i] = false;
    }
    cnt[nod] = 1;
    v[nod] = true;
    Q.push(nod);
    while(!Q.empty()) {
        nod = Q.front();
        Q.pop();
        for(auto it : G[nod]) {
            if(!v[it]) {
                cnt[it] = cnt[nod] + 1;
                Q.push(it);
                v[it] = true;
                d = cnt[it];
                ult = it;
            }
        }
    }
}

int main() {
    fin >> n;
    for(int i = 1; i <= n; i++) {
        int x, y;
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    bfs(1);
    bfs(ult);
    fout << d;
    return 0;
}