#include <bits/stdc++.h>
using namespace std;
const int N=100123, LOG=18;
int n,m,q;
int h[N], low[N], timer;
bool isBridge[N], vis[N];
int comp[N], compCnt;
int par[LOG][N], dep[N];
int man[N], mos[N];
struct Edge {
int to,id,nxt;
};
Edge edges[2*N];
int head[N], edge_cnt;
int uE[N], vE[N];
int ans[N];
void add_edge(int u,int v,int id){
edges[++edge_cnt] = {v,id,head[u]};
head[u] = edge_cnt;
edges[++edge_cnt] = {u,id,head[v]};
head[v] = edge_cnt;
}
void find_bridges(int v,int p,int pId){
vis[v]=true;
h[v] = p == -1 ? 0 : h[p] + 1;
low[v] = h[v];
for(int i=head[v]; i; i=edges[i].nxt){
int to=edges[i].to, idx=edges[i].id;
if(idx == pId) continue;
if(!vis[to]){
find_bridges(to,v,idx);
low[v] = min(low[v], low[to]);
if(low[to] > h[v]) isBridge[idx] = true;
}else if(to != p){
low[v] = min(low[v], h[to]);
}
}
}
void dfs_comp(int v){
comp[v] = compCnt;
for(int i=head[v]; i; i=edges[i].nxt){
int to=edges[i].to;
if(comp[to] == -1 && !isBridge[edges[i].id]){
dfs_comp(to);
}
}
}
void dfs_lca_prep(int v,int p){
vis[v] = true;
par[0][v] = p;
for(int i=1; i<LOG; i++){
if(par[i-1][v] == -1) par[i][v] = -1;
else par[i][v] = par[i-1][par[i-1][v]];
}
for(int i=head[v]; i; i=edges[i].nxt){
int to=edges[i].to;
if(to != p && !vis[to]){
dep[to] = dep[v] + 1;
dfs_lca_prep(to,v);
}
}
man[v] = mos[v] = 1e9;
}
int jump(int v,int d){
for(int i=0; i<LOG; i++) if(d & (1<<i)) v = par[i][v];
return v;
}
int lca(int u,int v){
if(dep[u] < dep[v]) swap(u,v);
u = jump(u, dep[u]-dep[v]);
if(u == v) return u;
for(int i=LOG-1; i>=0; i--){
if(par[i][u] != par[i][v]){
u = par[i][u];
v = par[i][v];
}
}
return par[0][u];
}
void dfs_propagate(int v,int p,int id=0){
vis[v] = true;
for(int i=head[v]; i; i=edges[i].nxt){
int to=edges[i].to, idx=edges[i].id;
if(to != p && !vis[to]){
dfs_propagate(to,v,idx);
man[v] = min(man[v], man[to]);
mos[v] = min(mos[v], mos[to]);
}
}
if(id){
int a = comp[uE[id]], b = comp[vE[id]];
if(man[v] != 1e9) ans[id] = (a == p ? 1 : 2);
else if(mos[v] != 1e9) ans[id] = (a == p ? 2 : 1);
else ans[id] = 0;
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
edge_cnt = 0;
memset(head,0,sizeof(head));
for(int i=1; i<=m; i++){
int a,b; cin >> a >> b;
uE[i] = a; vE[i] = b;
add_edge(a,b,i);
isBridge[i] = false;
ans[i] = 0;
}
memset(vis,0,sizeof(vis));
for(int i=1; i<=n; i++){
if(!vis[i]) find_bridges(i,-1,-1);
}
// Build components by contracting non-bridge edges
memset(comp,-1,sizeof(comp));
compCnt = 0;
memset(head,0,sizeof(head));
edge_cnt = 0;
// Add only non-bridge edges for components
for(int i=1; i<=m; i++){
if(!isBridge[i]){
add_edge(uE[i], vE[i], i);
add_edge(vE[i], uE[i], i); // added for undirected DFS
}
}
memset(vis,0,sizeof(vis));
for(int i=1; i<=n; i++){
if(comp[i] == -1){
compCnt++;
dfs_comp(i);
}
}
// Build bridge tree with components as nodes
memset(head,0,sizeof(head));
edge_cnt = 0;
memset(vis,0,sizeof(vis));
for(int i=1; i<=compCnt; i++){
man[i] = mos[i] = 1e9;
}
for(int i=1; i<=m; i++){
if(isBridge[i]){
int a = comp[uE[i]], b = comp[vE[i]];
add_edge(a,b,i);
}
}
// Prepare LCA on bridge tree
memset(vis,0,sizeof(vis));
for(int i=1; i<=compCnt; i++){
if(!vis[i]){
dep[i] = 0;
dfs_lca_prep(i, -1);
}
}
cin >> q;
for(int i=0; i<q; i++){
int a,b; cin >> a >> b;
a = comp[a]; b = comp[b];
if(a == b) continue;
int w = lca(a,b);
man[b] = min(man[b], dep[w]);
mos[a] = min(mos[a], dep[w]);
}
memset(vis,0,sizeof(vis));
for(int i=1; i<=compCnt; i++){
if(!vis[i]){
dfs_propagate(i, -1);
}
}
// Output final directions
for(int i=1; i<=m; i++){
if(!isBridge[i]) cout << 'B';
else if(ans[i] == 1) cout << 'R';
else if(ans[i] == 2) cout << 'L';
else cout << 'B';
}
cout << '\n';
return 0;
}
