#include <bits/stdc++.h> using namespace std; using pi = pair<int, int>; using vi = vector<int>; using vvi = vector<vi>; using vpi = vector<pi>; int n, m, p, timer = 0, cid = 0; vvi G; vi X, Y, tin, low, vis, cmp; vpi pairs; void dfs(int u, int p) { tin[u] = timer++; vis[u]++; for (auto e : G[u]) { int v = X[e] == u ? Y[e] : X[e]; if (v == p || v == u) continue; if (vis[v]) { low[u] = min(low[u], tin[v]); continue; } dfs(v, u); low[u] = min(low[u], low[v]); } } const int maxlog = 18; int tree_timer = 0; vi tree_tin, tree_tout, par_edge, depth; vvi up, adj; void assign(int u, int id) { cmp[u] = id; for (auto e : G[u]) { int v = X[e] == u ? Y[e] : X[e]; if ((tin[u] < tin[v] && low[v] > tin[u]) || (tin[v] < tin[u] && low[u] > tin[v])) { if (cmp[u] != -1 && cmp[v] != -1) { adj[cmp[u]].push_back(e); adj[cmp[v]].push_back(e); } continue; } if (cmp[v] != -1) continue; assign(v, id); } } void dfs2(int u, int p) { tree_tin[u] = tree_timer++; up[u][0] = p; depth[u] = depth[p] + 1; for (int i = 1; i < maxlog; i++) up[u][i] = up[up[u][i-1]][i-1]; for (auto e : adj[u]) { int a = cmp[X[e]], b = cmp[Y[e]]; int v = a == u ? b : a; if (v == p) continue; par_edge[v] = e; dfs2(v, u); } tree_tout[u] = tree_timer; } bool is_ancestor(int u, int v) { return tree_tin[u] <= tree_tin[v] && tree_tout[u] >= tree_tout[v]; } int lca(int u, int v) { if (is_ancestor(u, v)) return u; if (is_ancestor(v, u)) return v; for (int i = maxlog-1; i >= 0; i--) { if (!is_ancestor(up[u][i], v)) u = up[u][i]; } return up[u][0]; } struct DSU { int n; vi par; DSU(int N = 0) : n(N), par(N) {for (int i = 0; i < n; i++) par[i] = i;} int find(int v) {return par[v] == v ? v : par[v] = find(par[v]);} void unite(int a, int b) {if (find(a) != find(b)) par[find(b)] = find(a);} }; int main() { cin.tie(0)->sync_with_stdio(0); cin >> n >> m; G.assign(n+1, vi()); X.resize(m); Y.resize(m); for (int i = 0; i < m; i++) { cin >> X[i] >> Y[i]; G[X[i]].push_back(i); G[Y[i]].push_back(i); } cin >> p; pairs.resize(p); for (int i = 0; i < p; i++) cin >> pairs[i].first >> pairs[i].second; tin.assign(n+1, INT_MIN); low.assign(n+1, INT_MAX); cmp.assign(n+1, -1); vis.assign(n+1, 0); for (int i = 1; i <= n; i++) if (!vis[i]) dfs(i, -1); tree_tin.assign(n+1, -1); tree_tout.assign(n+1, -1); par_edge.assign(n+1, -1); depth.assign(n+1, -1); adj.resize(n+1); up.assign(n+1, vi(maxlog, -1)); for (int i = 1; i <= n; i++) if (cmp[i] == -1) assign(i, cid++); for (int i = 1; i <= n; i++) if (tree_tin[cmp[i]] == -1) dfs2(cmp[i], cmp[i]); string ans(m, 'B'); auto dsu = DSU(n+1); for (auto &[u, v] : pairs) { int x = cmp[u], y = cmp[v]; if (x == y) continue; int A = lca(x, y); x = dsu.find(x); y = dsu.find(y); while (depth[x] > depth[A]) { bool left = cmp[X[par_edge[x]]] == x; int p = left ? cmp[Y[par_edge[x]]] : cmp[X[par_edge[x]]]; ans[par_edge[x]] = !left ? 'L' : 'R'; dsu.unite(p, x); x = dsu.find(x); } while (depth[y] > depth[A]) { bool left = cmp[X[par_edge[y]]] == y; int p = left ? cmp[Y[par_edge[y]]] : cmp[X[par_edge[y]]]; ans[par_edge[y]] = left ? 'L' : 'R'; dsu.unite(p, y); y = dsu.find(y); } } cout << ans << "\n"; return 0; }