Code

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

class UnionFind {
  public:
    int n;
    vector<int> parent;
    UnionFind(int n) {
        this->n = n;
        parent.resize(n);
        for (int i = 0; i < n; i++) {
            parent[i] = i;
        }
    }

  public:
    int find_set(int u) {
        if (parent[u] == u) {
            return u;
        }

        int root_x = find_set(parent[u]);
        parent[u] = root_x;
        return root_x;
    }

    void union_sets(int a, int b) {
        a = find_set(a);
        b = find_set(b);

        if (a != b) {
            parent[a] = b;
        }
    }
};

void solve() {
    int n, m;
    cin >> n >> m;

    UnionFind dsu(n);
    for (int i = 0; i < m; i++) {
        int x, y;
        cin >> x >> y;
        x--;
        y--;
        dsu.union_sets(x, y);
    }

    int k;
    cin >> k;
    set<pair<int, int>> restricted;
    for (int i = 0; i < k; i++) {
        int x, y;
        cin >> x >> y;
        x--;
        y--;
        restricted.insert({dsu.find_set(x), dsu.find_set(y)});
        restricted.insert({dsu.find_set(y), dsu.find_set(x)});
    }

    int q;
    cin >> q;
    for (int i = 0; i < q; i++) {
        int p, q;
        cin >> p >> q;
        p--;
        q--;
        if (restricted.find({dsu.find_set(p), dsu.find_set(q)}) !=
            restricted.end()) {
            cout << "No" << endl;
        } else {
            cout << "Yes" << endl;
        }
    }
}

int main() {
    solve();
    return 0;
}