Gym 101848C

#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long

template<typename T>
inline void read(T&x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

const int N=1e6+7;

stack<int> sta[N];
vector<int> G[N];
vector<int> func[N];
vector<pair<int,int> >query[N];

int ans[N];

void dfs(int x){
    for(int i=0;i<func[x].size();++i){
        sta[func[x][i]].push(x);
    }
    for(int i=0;i<query[x].size();++i){
        ans[query[x][i].second]=sta[query[x][i].first].size()?sta[query[x][i].first].top():-1;
    }
    for(int i=0;i<G[x].size();++i){
        dfs(G[x][i]);
    }
    for(int i=0;i<func[x].size();++i){
        sta[func[x][i]].pop();
    }
}

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    int n;r(n);
    for(int i=2;i<=n;++i){
        int f;r(f);
        G[f].push_back(i);
    }
    for(int i=1;i<=n;++i){
        int x;r(x);
        while(x--){
            int t;r(t);
            func[i].push_back(t);
        }
    }
    int q;r(q);
    for(int i=1;i<=q;++i){
        int x,y;r(x),r(y);
        query[x].push_back(make_pair(y,i));
    }
    dfs(1);
    for(int i=1;i<=q;++i){
        printf("%d\n",ans[i]);
    }
    return 0;
}