#include <bits/stdc++.h>
#define fi first
#define se second
#define FOR(i, a, b) for(int i=(a); i<=(b); ++i)
#define REP(i, a, b) for(int i=(a); i>=(b); --i)
#define umax(x, y) x = max(x, (y))
#define umin(x, y) x = min(x, (y))
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(i) (1LL << (i))
#define sz(v) (int)(v).size()
#define ALL(v) (v).begin(),(v).end()
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const int N = 1e6 + 5;
const int mod = 1e9 + 7;
const int base = 311;
const ll INF = 1e18;
// Author: rexdino
int n, m, p;
pii edges[N];
vector<int> adj[N];
int tin[N], tout[N], Timer, par[22][N], low[N], h[N];
int id[N], cnt, dp[N], up[N], down[N];
bool del[N];
char ans[N];
void dfs(int u){
tin[u] = low[u] = ++Timer;
for (int id : adj[u]){
int v = edges[id].fi + edges[id].se - u;
if (v != par[0][u]){
if (!tin[v]){
par[0][v] = u;
dfs(v);
umin(low[u], low[v]);
dp[u] += dp[v];
up[u] += up[v];
down[u] += down[v];
if (low[v] <= tin[u]) continue;
cerr << id << ": " << u << " " << v << ": " << up[v] << " " << down[v] << "\n";
// cerr << u << " " << v << "\n";
if (up[v]) {
if (edges[id].fi == u) ans[id] = 'L';
else ans[id] = 'R';
} else if (down[v]) {
if (edges[id].fi == u) ans[id] = 'R';
else ans[id] = 'L';
} else ans[id] = 'B';
} else umin(low[u], tin[v]);
}
}
tout[u] = Timer;
}
bool isAnc(int u, int v){
return tin[u] <= tin[v] && tin[v] <= tout[u];
}
int lca(int u, int v){
if (isAnc(u, v)) return u;
if (isAnc(v, u)) return v;
REP(i, 20, 0) if (!isAnc(par[i][u], v)) u = par[i][u];
return par[0][u];
}
void solve(){
cin >> n >> m;
FOR(i, 1, m){
int u, v;
cin >> u >> v;
edges[i] = {u, v};
adj[u].push_back(i);
adj[v].push_back(i);
}
FOR(i, 1, n) if (!tin[i]) {
par[0][i] = i;
dfs(i);
}
FOR(i, 1, 20) FOR(u, 1, n) par[i][u] = par[i - 1][par[i - 1][u]];
cin >> p;
while(p--){
int x, y;
cin >> x >> y;
int z = lca(x, y);
cerr << "lca " << x << " " << y << ": " << z << "\n";
up[x]++;
up[z]--;
down[y]++;
down[z]--;
}
cerr << "\n";
Timer = 0;
memset(tin, 0, sizeof tin);
FOR(i, 1, n) if (!tin[i]) dfs(i);
FOR(i, 1, m){
if (ans[i] != 'R' && ans[i] != 'L') ans[i] = 'B';
cout << ans[i];
}
}
signed main(){
#define NAME "main"
if (fopen(NAME".inp", "r")){
freopen(NAME".inp", "r", stdin);
freopen(NAME".out", "w", stdout);
}
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int t = 1;
// cin >> t;
while(t--) solve();
// cerr << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << "s\n";
return 0;
}
