#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#ifdef DEBUG
#include <time.h>
#endif
#define all(a) (a).begin(), (a).end()
#define rev(a) (a).rbegin(), (a).rend()
#define F first
#define S second
int recur_depth = 0;
#ifdef DEBUG
#define dbg(x) \
{ \
++recur_depth; \
auto x_ = x; \
--recur_depth; \
cerr << string(recur_depth, '\t') << "\e[91m" << __func__ << ":" \
<< __LINE__ << "\t" << #x << " = " << x_ << "\e[39m" << endl; \
}
#else
#define dbg(x)
#endif
using namespace std;
using namespace __gnu_pbds;
typedef pair<int, int> ii;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> llll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pair<int, int>> vii;
typedef vector<vii> vvii;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pair<ll, ll>> vll;
typedef vector<vll> vvll;
typedef vector<bool> vb;
template <class type1>
using ordered_set = tree<type1, null_type, less<type1>, rb_tree_tag,
tree_order_statistics_node_update>;
template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p) {
return os << '(' << p.first << ", " << p.second << ')';
}
template <typename T_container, typename T = typename enable_if<
!is_same<T_container, string>::value,
typename T_container::value_type>::type>
ostream &operator<<(ostream &os, const T_container &v) {
os << '{';
string sep;
for (const T &x : v)
os << sep << x, sep = ", ";
return os << '}';
}
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll INF = 1e9;
const ld EPS = 1e-9;
struct Edge {
int u, v, idx, res = 2;
bool is_bridge;
};
struct ST {
const int MAXLG = 22;
int n;
vi lg2;
vvii st;
ST(int n, vii &a) : n(n) {
st = vvii(MAXLG, vii(n));
st[0] = a;
for (int j = 1; j < MAXLG; j++)
for (int i = 0; i + (1 << j) <= n; i++)
st[j][i] = min(st[j - 1][i], st[j - 1][i + (1 << (j - 1))]);
lg2 = vi(n + 2);
lg2[1] = 0;
for (int i = 2; i <= n; i++)
lg2[i] = lg2[i / 2] + 1;
}
int query(int l, int r) {
if (l > r)
swap(l, r);
int k = lg2[r - l + 1];
return min(st[k][l], st[k][r - (1 << k) + 1]).second;
}
};
void solve() {
int n, m;
cin >> n >> m;
vector<Edge> eds(m);
vvii adj(n);
for (int i = 0; i < m; i++) {
Edge &e = eds[i];
cin >> e.u >> e.v;
e.u--, e.v--;
e.idx = i;
adj[e.u].push_back({e.v, i});
adj[e.v].push_back({e.u, i});
}
int p;
cin >> p;
vi st(p), en(p);
for (int i = 0; i < p; i++)
cin >> st[i] >> en[i], st[i]--, en[i]--;
int timer = 0;
vi tin(n), low(n);
vb vis(n);
function<void(int, int)> f = [&](int u, int p_e_id) {
vis[u] = 1;
tin[u] = low[u] = timer++;
for (auto [v, i] : adj[u])
if (i != p_e_id) {
if (vis[v])
low[u] = min(low[u], low[v]);
else {
f(v, i);
low[u] = min(low[u], low[v]);
if (low[v] > tin[u])
eds[i].is_bridge = 1;
}
}
};
for (int i = 0; i < n; i++)
if (!vis[i])
f(i, -1);
vis = vb(n);
vi cc_id(n);
function<void(int, int)> g = [&](int u, int c_id) {
vis[u] = 1;
cc_id[u] = c_id;
for (auto [v, i] : adj[u])
if (!vis[v] && !eds[i].is_bridge)
g(v, c_id);
};
int cidx = 0;
for (int i = 0; i < n; i++)
if (!vis[i])
g(i, cidx++);
vvii tree(cidx);
for (Edge e : eds)
if (cc_id[e.u] != cc_id[e.v]) {
tree[cc_id[e.u]].push_back({cc_id[e.v], e.idx});
tree[cc_id[e.v]].push_back({cc_id[e.u], e.idx});
}
for (int i = 0; i < cidx; i++) {
sort(all(tree[i]));
tree[i].erase(unique(all(tree[i])), tree[i].end());
}
vi depth(cidx), first_occ(cidx), cnt_child(cidx);
vii par(cidx, {-1, -1}), euler;
vis = vb(cidx);
function<void(int, int)> h = [&](int u, int p) {
vis[u] = 1;
first_occ[u] = euler.size();
euler.push_back({depth[u], u});
for (auto [v, i] : tree[u])
if (v != p) {
par[v] = {u, i};
cnt_child[u]++;
depth[v] = depth[u] + 1;
h(v, u);
euler.push_back({depth[u], u});
}
};
vi roots;
for (int i = 0; i < cidx; i++)
if (!vis[i])
roots.push_back(i), h(i, -1);
ST s(euler.size(), euler);
vi no_st(cidx), no_en(cidx);
for (int i = 0; i < p; i++)
if (cc_id[st[i]] != cc_id[en[i]]) {
int st_cc = cc_id[st[i]], en_cc = cc_id[en[i]];
int lca = s.query(first_occ[st_cc], first_occ[en_cc]);
no_st[st_cc]++, no_en[en_cc]++;
no_st[lca]--, no_en[lca]--;
}
function<void(int, int)> d = [&](int u, int p) {
for (auto [v, i] : tree[u])
if (v != p) {
d(v, u);
no_st[u] += no_st[v];
no_en[u] += no_en[v];
}
};
for (int root : roots)
d(root, -1);
for (int i = 0; i < cidx; i++) {
auto [p, peid] = par[i];
if (p < 0)
continue;
if (no_st[i]) {
if (cc_id[eds[peid].u] == i)
eds[peid].res = 0;
else
eds[peid].res = 1;
continue;
}
if (no_en[i]) {
if (cc_id[eds[peid].u] == i)
eds[peid].res = 1;
else
eds[peid].res = 0;
}
}
for (Edge &e : eds) {
if (e.res == 2)
cout << "B";
else if (e.res == 0)
cout << "R";
else
cout << "L";
}
cout << "\n";
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
clock_t start = clock();
int test_cases = 1;
// cin >> test_cases;
while (test_cases--)
solve();
#ifdef DEBUG
cerr << fixed << setprecision(10)
<< "\nTime Taken: " << (double)(clock() - start) / CLOCKS_PER_SEC
<< "s\n";
#endif
return 0;
}
