#include <bits/stdc++.h>
using namespace std;
const int N=1e5+4,LG=ceil(log2(N))+1;
vector<int>g[N],spn[N],up[N],X[N],Y[N];
multiset<int>upp[N];
set<array<int,2>>edges;
int n,m,p,par[N],dep[N],vis[N],mxX[N],mxY[N],mxB[N],tout[N],tin[N],ti;
int cale[LG][N];
void construct(int u){
vis[u]=1;
for(int v:g[u]){
if(!vis[v]){
par[v]=u;
spn[u].push_back(v);
spn[v].push_back(u);
dep[v]=dep[u]+1;
construct(v);
}
}
}
void makett(int u,int p=0){
tin[u]=++ti;
vis[u]=1;
cale[0][u]=p;
for(int i=1;i<LG;++i)
cale[i][u]=cale[i-1][cale[i-1][u]];
for(int v:spn[u])
if(!vis[v])
makett(v,u);
tout[u]=++ti;
}
bool iznad(int a,int b){
return tin[a]<=tin[b]&&tout[b]<=tout[a];
}
int lca(int a,int b){
if(iznad(a,b))
return a;
if(iznad(b,a))
return b;
for(int i=LG-1;i>=0;--i){
if(!iznad(cale[i][b],a)&&cale[i][b])
b=cale[i][b];
}
return cale[0][b];
}
multiset<array<int,2>>back;
map<array<int,2>,char>sol;
vector<array<int,2>>o;
void dfs(int u){
vis[u]=1;
mxB[u]=1e9;
for(int v:up[u]){
if(mxB[u]==1e9||dep[v]<dep[mxB[u]])
mxB[u]=v;
}
mxX[u]=1e9;
for(int v:X[u]){
if(!iznad(u,v)&&!iznad(v,u)){
int nw=lca(u,v);
if(mxX[u]==1e9||dep[mxX[u]]>dep[nw])
mxX[u]=nw;
continue;
}
if(dep[v]>dep[u])continue;
if(mxX[u]==1e9||dep[mxX[u]]>dep[v])
mxX[u]=v;
}
mxY[u]=1e9;
for(int v:Y[u]){
if(!iznad(u,v)&&!iznad(v,u)){
int nw=lca(u,v);
if(mxY[u]==1e9||dep[mxY[u]]>dep[nw])
mxY[u]=nw;
continue;
}
if(dep[v]>dep[u])continue;
if(mxY[u]==1e9||dep[mxY[u]]>dep[v])
mxY[u]=v;
}
for(int v:spn[u]){
if(vis[v])
continue;
dfs(v);
if(mxB[u]==1e9||(mxB[v]!=1e9&&dep[mxB[v]]<dep[mxB[u]]))mxB[u]=mxB[v];
if(mxX[u]==1e9||(mxX[v]!=1e9&&dep[mxX[v]]<dep[mxX[u]]))mxX[u]=mxX[v];
if(mxY[u]==1e9||(mxY[v]!=1e9&&dep[mxY[v]]<dep[mxY[u]]))mxY[u]=mxY[v];
}
}
char get(int u,int v){
if(back.find({u,v})!=back.end()){
back.erase(back.find({u,v}));
back.erase(back.find({v,u}));
return'B';
}
if(!sol[{u,v}]&&!sol[{v,u}])return'B';
if(v==par[u])return sol[{u,v}];
else return (sol[{v,u}]=='R'?'L':sol[{v,u}]=='B'?'B':'R');
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
cin>>n>>m;
for(int i=0,u,v;i<m;++i){
cin>>u>>v;
o.push_back({u,v});
g[u].push_back(v);
g[v].push_back(u);
upp[u].insert(v);
upp[v].insert(u);
back.insert({u,v});
back.insert({v,u});
}
cin>>p;
for(int i=0,x,y;i<p;++i){
cin>>x>>y;
X[x].push_back(y);
Y[y].push_back(x);
}
for(int i=1;i<=n;++i){
if(!vis[i])
construct(i);
}
fill(vis,vis+N,0);
for(int i=1;i<=n;++i){
if(!vis[i])
makett(i);
}
for(int i=1;i<=n;++i){
for(int j:spn[i]){
back.erase(back.find({i,j}));
upp[i].erase(upp[i].find(j));
}
}
tin[0]=-1e9;
tout[0]=1e9;
for(int i=1;i<=n;++i){
vector<int>toer;
for(int j:upp[i])
if(j!=i&&iznad(i,j))
toer.push_back(j);
for(int j:toer)
upp[i].erase(upp[i].find(j));
}
for(int i=1;i<=n;++i){
for(int j:upp[i])
up[i].push_back(j);
}
fill(vis,vis+N,0);
for(int i=1;i<=n;++i){
if(!vis[i])
dfs(i);
}
for(int i=2;i<=n;++i){
if(mxB[i]!=1e9&&dep[mxB[i]]<=dep[par[i]])
sol[{i,par[i]}]='B';
else if(mxX[i]!=1e9&&dep[mxX[i]]<=dep[par[i]])
sol[{i,par[i]}]='R';
else if(mxY[i]!=1e9&&dep[mxY[i]]<=dep[par[i]])
sol[{i,par[i]}]='L';
else
sol[{i,par[i]}]='B';
}
for(auto [u,v]:o)
cout<<get(u,v);
}
