#include <bits/stdc++.h> #define ll long long using namespace std; const int mxN = 1e5+5; int n, m, dep[mxN], cnt[mxN], PU[mxN], PD[mxN], id[mxN], ans[mxN], it = 0, up[30][mxN]; vector <pair <int, int>> adj[mxN], adt[mxN]; void dfs(int u, int p, int ii) { id[u] = ++it; dep[u] = dep[p]+1; up[0][u] = p; for (auto [v, idx] : adj[u]) if (abs(idx) != abs(ii)) { if (id[v]) { if (id[v] > id[u]) cnt[u]--, ans[abs(idx)] = 3; else if (id[v] < id[u]) cnt[u]++, ans[abs(idx)] = 3; else if (id[v] == id[u]) ans[abs(idx)] = 3; } else { dfs(v, u, idx); if (cnt[v] > 0) ans[abs(idx)] = 3; cnt[u] += cnt[v]; adt[u].emplace_back(v, idx); } } // cout << "DFS : " << u << ' ' << cnt[u] << '\n'; } int LCA(int u, int v) { if (dep[u] < dep[v]) swap(u, v); int k = dep[u] - dep[v]; for (int i = 0; i < 30; i++) if (k & (1 << i)) u = up[i][u]; if (u == v) return u; for (int i = 29; i >= 0; i--) if (up[i][u] != up[i][v]) u = up[i][u], v = up[i][v]; return up[0][u]; } set <int> U[mxN], D[mxN]; void dfs2(int u, int p) { for (auto [v, idx] : adt[u]) { dfs2(v, u); if (ans[abs(idx)] == 0 && U[v].size()) ans[abs(idx)] = (idx < 0 ? 1 : 2); if (ans[abs(idx)] == 0 && D[v].size()) ans[abs(idx)] = (idx < 0 ? 2 : 1); if (U[v].size() > U[u].size()) swap(U[u], U[v]); for (auto &e : U[v]) U[u].emplace(e); if (D[v].size() > D[u].size()) swap(D[u], D[v]); for (auto &e : D[u]) D[u].emplace(e); U[v].clear(), D[v].clear(); } if (PU[u] != dep[u]) U[u].emplace(PU[u]); if (PD[u] != dep[u]) D[u].emplace(PD[u]); if (U[u].find(dep[u]) != U[u].end()) U[u].erase(U[u].find(dep[u])); if (D[u].find(dep[u]) != D[u].end()) D[u].erase(D[u].find(dep[u])); // cout << u << " : \n"; // for (auto &e : U[u]) cout << e << ' '; cout << '\n'; // for (auto &e : D[u]) cout << e << ' '; cout << '\n'; } int main() { ios::sync_with_stdio(0), cin.tie(0); cin >> n >> m; for (int i = 1, u, v; i <= m; i++) cin >> u >> v, adj[u].emplace_back(v, i), adj[v].emplace_back(u, -i); dfs(1, 0, INT_MIN); // for (int i = 1; i <= m; i++) cout << ans[i] << ' '; cout << '\n'; int q; cin >> q; for (int i = 1; i <= n; i++) PU[i] = PD[i] = dep[i]; for (int c = 1; c < 30; c++) for (int i = 1; i <= n; i++) up[c][i] = up[c-1][up[c-1][i]]; while (q--) { int u, v; cin >> u >> v; int lca = LCA(u, v); // cout << u << ' ' << v << ' ' << lca << '\n'; PU[u] = min(PU[u], dep[lca]); PD[v] = min(PD[v], dep[lca]); } // for (int i = 1; i <= n; i++) cout << PU[i] << ' ' << PD[i] << '\n'; dfs2(1, 0); for (int i = 1; i <= m; i++) { if (ans[i] == 1) cout << 'L'; else if (ans[i] == 2) cout << 'R'; else cout << 'B'; } cout << '\n'; }