This documentation is automatically generated by online-judge-tools/verification-helper
#define PROBLEM "https://onlinejudge.u-aizu.ac.jp/courses/library/5/GRL/all/GRL_5_C"
#include "../memo/macro.hpp"
#include "../data_structure/sparse_table.cpp"
#include "../graph/LCA_sparsetable.cpp"
signed main(void) {
ll n;
cin >> n;
LCA graph(n);
REP(i, n) {
ll k;
cin >> k;
REP(j, k) {
ll c;
cin >> c;
graph.add_edge(i, c);
}
}
graph.build();
ll q;
cin >> q;
while(q--) {
ll u, v;
cin >> u >> v;
cout << graph.get(u, v) << endl;
}
return 0;
}
#line 1 "test/GRL5C_2.test.cpp"
#define PROBLEM "https://onlinejudge.u-aizu.ac.jp/courses/library/5/GRL/all/GRL_5_C"
#line 1 "memo/macro.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using PII = pair<ll, ll>;
#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
template<typename T> void chmin(T &a, const T &b) { a = min(a, b); }
template<typename T> void chmax(T &a, const T &b) { a = max(a, b); }
struct FastIO {FastIO() { cin.tie(0); ios::sync_with_stdio(0); }}fastiofastio;
const ll INF = 1LL<<60;
#line 1 "data_structure/sparse_table.cpp"
// BEGIN CUT
template <typename S>
struct sparseTable {
using T = typename S::T;
int n;
vector<int> log2;
vector<vector<T>> t;
sparseTable() {}
sparseTable(int nn) { construct(nn); }
void construct(int nn) {
n = nn;
log2.assign(n+1, 0);
for(int i=2; i<=n; ++i) log2[i] = log2[i >> 1] + 1;
t = vector<vector<T>>(log2[n]+1, vector<T>(n));
}
void init(vector<T> v) {
for(int i=0; i<n; ++i) t[0][i] = v[i];
for(int j=1; j<=log2[n]; ++j) {
int w = 1LL<<(j-1);
for (int i = 0; i+(w<<1) <= n; ++i) {
t[j][i] = S::op(t[j-1][i], t[j-1][i+w]);
}
}
}
// [l, r]
T query(int l, int r) {
int j = log2[r - l];
return S::op(t[j][l], t[j][r-(1 << j)+1]);
}
};
// 集合T、結合則・可換・冪等律が成り立つ二項演算op
struct minnimum {
using T = ll;
static T op(const T& a, const T& b) { return min(a, b); }
};
struct maximum {
using T = ll;
static T op(const T& a, const T& b) { return max(a, b); }
};
struct gcd_op {
using T = ll;
static T op(const T& a, const T& b) { return __gcd(a, b); }
};
// END CUT
#line 1 "graph/LCA_sparsetable.cpp"
// BEGIN CUT
class LCA {
private:
const int n = 0;
const int log2_n = 0;
vector<vector<int>> par;
vector<vector<int>> g;
vector<int> depth; // 頂点iの深さ
vector<int> vs; // 頂点を訪問順に並べたもの
vector<int> depth_seq; // depth_seq[i] = (頂点vs[i]の深さ)
vector<int> id; // 頂点が初めてvsに登場するインデックス
struct minimum_st {
using T = PII;
static T op(const T& a, const T& b) { return min(a, b); }
};
sparseTable<minimum_st> st;
void dfs(int v, int p, int d, int &k) {
id[v] = k; vs[k] = v; depth_seq[k++] = d; depth[v] = d;
for(auto to: g[v]) if(to != p) {
dfs(to, v, d+1, k);
vs[k] = v; depth_seq[k++] = d;
}
}
public:
LCA(int n_=1e5) : n(n_), g(n), depth(n), vs(2*n-1), depth_seq(2*n-1), id(n) {}
// u-vに辺を張る
void add_edge(int u, int v) {
g[u].push_back(v);
g[v].push_back(u);
}
// rootを根として初期化
void build(int root = 0) {
int k = 0;
dfs(root, -1, 0, k);
vector<PII> v(2*n-1);
REP(i, 2*n-1) v[i] = {depth_seq[i], i};
st.construct(2*n-1);
st.init(v);
}
// uとvのlcaを返す O(1)
int get(int u, int v) {
if(id[u] > id[v]) swap(u, v);
return vs[st.query(id[u], id[v]).second];
}
};
// END CUT
#line 5 "test/GRL5C_2.test.cpp"
signed main(void) {
ll n;
cin >> n;
LCA graph(n);
REP(i, n) {
ll k;
cin >> k;
REP(j, k) {
ll c;
cin >> c;
graph.add_edge(i, c);
}
}
graph.build();
ll q;
cin >> q;
while(q--) {
ll u, v;
cin >> u >> v;
cout << graph.get(u, v) << endl;
}
return 0;
}