#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
using ld = long double;
using ii = pair<int, int>;
const int N = 1e5 + 100;
int n, m, q, in[N], out[N], low[N], t, dir[N];
bool flag[N];
vector<tuple<int, int, int>> g[N];
vector<int> to[N], from[N];
ii mi[N], ma[N];
void preProcess(int u, int p = -1) {
in[u] = out[u] = t++;
for(auto [v, e, f] : g[u]) {
if(in[v] < 0) {
preProcess(v, u);
out[u] = out[v];
}
}
}
void dfs(int u, int p = -1) {
low[u] = t++;
mi[u] = ii(n, -1);
ma[u] = ii(-1, -1);
for(auto [v, e, f] : g[u]) {
if(low[v] < 0) {
dfs(v, u);
mi[u] = min(mi[u], mi[v]);
ma[u] = max(ma[u], ma[v]);
if(low[v] > in[u]) {
if(mi[v].first < in[v]) {
auto [t, ff] = mi[v];
dir[e] = f * ff;
}
if(ma[v].first > out[v]) {
auto [t, ff] = ma[v];
dir[e] = f * ff;
}
}
low[u] = min(low[u], low[v]);
} else {
if(!(v == p && !flag[u])) low[u] = min(low[u], in[v]);
if(v == p) flag[u] = true;
}
}
for(int v : to[u]) {
mi[u] = min(mi[u], ii(in[v], -1));
ma[u] = max(ma[u], ii(in[v], -1));
}
for(int v : from[u]) {
mi[u] = min(mi[u], ii(in[v], 1));
ma[u] = max(ma[u], ii(in[v], 1));
}
}
void solve() {
cin >> n >> m;
memset(in, -1, sizeof(int) * n);
memset(low, -1, sizeof(int) * n);
for(int i = 0; i < m; ++i) {
int u, v;
cin >> u >> v;
--u, --v;
if(u != v) {
g[u].emplace_back(v, i, 1);
g[v].emplace_back(u, i, -1);
}
}
cin >> q;
while(q--) {
int x, y;
cin >> x >> y;
--x, --y;
to[x].push_back(y);
from[y].push_back(x);
}
for(int i = 0; i < n; ++i) if(in[i] < 0) preProcess(i);
t = 0;
for(int i = 0; i < n; ++i) if(low[i] < 0) dfs(i);
string ans;
for(int i = 0; i < m; ++i) {
if(dir[i] == -1) ans += 'L';
else if(dir[i] == 1) ans += 'R';
else ans += 'B';
}
cout << ans << '\n';
}
int main() {
ios_base :: sync_with_stdio(false);
cin.tie(0);
int t = 1;
//cin >> t;
while(t--) solve();
return 0;
}
