//Huyduocdithitp
#include<bits/stdc++.h>
typedef int ll;
#define endl '\n'
#define fi first
#define se second
#define pii pair<int, int>
#define N 100005
#define LOG 18
using namespace std;
bool ghuy4g;
struct Canh {
ll u, v, id;
} canh[N];
pii kq[N];
vector<pii> adj[N], adj2[N];
ll n, m, q, high[N];
ll num[N], low[N], timeDfs, par[N], Par[N][LOG + 2];
bool vst[N];
void dfs2(ll u, ll parent) {
vst[u] = 1;
//cout << u << " high " << high[u] << endl;
for (auto v : adj2[u]) {
if (v.fi == parent) continue;
Par[v.fi][0] = u;
high[v.fi] = high[u] + 1;
dfs2(v.fi, u);
}
}
ll find(ll u) {
if (par[u] < 0) return u;
return par[u] = find(par[u]);
}
void join(ll u, ll v) {
u = find(u);
v = find(v);
if (u == v) return;
if (par[u] <= par[v]) {
par[u] += par[v];
par[v] = u;
}
else {
par[v] += par[u];
par[u] = v;
}
}
ll mp[N], bcc, fl[N], fx[N], pl[N], px[N];
vector<ll> p[N];
vector<pii> lap;
void dfs(ll u, ll parent) {
low[u] = num[u] = ++ timeDfs;
for (auto vv : adj[u]) {
ll v = vv.fi;
if (v == parent) continue;
if (num[v]) {
join(u, v);
low[u] = min(low[u], num[v]);
}
else {
dfs(v, u);
low[u] = min(low[u], low[v]);
if (low[v] == num[v]) {
}
else {
join(u, v);
}
}
}
}
ll lca(ll u, ll v) {
if (high[u] > high[v]) swap(u, v);
for (int j = LOG; j >= 0; j --) {
if (high[v] - high[u] >= (1 << j)) {
v = Par[v][j];
}
}
if (u == v) return u;
for (int j = LOG; j >= 0; j --) {
if (Par[u][j] != Par[v][j]) {
u = Par[u][j];
v = Par[v][j];
}
}
return Par[u][0];
}
ll kth_par(ll u, ll k) {
for (int j = LOG; j >= 0; j --) {
if (k >= (1 << j)) {
k -= (1 << j);
u = Par[u][j];
}
}
return u;
}
void dfs3(ll u, ll parent) {
vst[u] = 1;
for (auto v : adj2[u]) {
if (v.fi == parent) continue;
dfs3(v.fi, u);
fx[u] += fx[v.fi];
fl[u] += fl[v.fi];
}
}
void pre() {
for (int i = 1; i <= n; i ++) {
if (num[i] == 0) {
dfs(i, i);
}
}
for (auto it : lap) {
join(it.fi, it.se);
}
map<ll, ll> mp1;
for (int i = 1; i <= n; i ++) {
ll r = find(i);
if (mp1[r] == 0) {
mp1[r] = ++ bcc;
}
mp[i] = mp1[r];
p[mp[i]].push_back(i);
//cout << i << " " << mp[i] << endl;
}
map<pii, pii> mp4;
//cout << "bcc " << bcc << endl;
for (int i = 1; i <= bcc; i ++) {
for (auto u : p[i]) {
//cout << "u " << u << endl;
for (auto v : adj[u]) {
//cout << "v " << v.fi << " " << v.se << endl;
//cout << u << " " << v.fi << " " << mp[u] << " " << mp[v.fi] << endl;
if (mp[v.fi] == mp[u]) continue;
//cout << u << " " << v.fi << " " << mp[u] << " " << mp[v.fi] << endl;
adj2[mp[u]].push_back({mp[v.fi], v.se});
//cout << mp[u] << " " << mp[v.fi] << endl;
mp4[{mp[u], mp[v.fi]}] = {u, v.fi};
//adj2[mp[v.fi]].push_back({mp[u], v.se});
}
}
//cout << endl;
}
for (int i = 1; i <= bcc; i ++) {
if (vst[i] == 0) dfs2(i, i);
}
for (int j = 1; j <= LOG; j ++) {
for (int i = 1; i <= bcc; i ++) {
ll P = Par[i][j - 1];
Par[i][j] = Par[P][j - 1];
}
}
for (int i = 1; i <= q; i ++) {
ll u, v;
cin >> u >> v;
if (mp[u] == mp[v]) continue;
u = mp[u];
v = mp[v];
ll x = lca(u, v);
fl[u] ++ ;
fl[x] -- ;
fx[v] ++ ;
fx[x] -- ;
}
for (int i = 1; i <= bcc; i ++) vst[i] = 0;
for (int i = 1; i <= bcc; i ++) {
if (vst[i] == 0) dfs3(i, i);
}
bool flag = 1;
for (int i = 1; i <= bcc; i ++) {
if (fx[i] > 0 && fl[i] > 0) {
flag = 0;
cout << -1;
exit(0);
}
if (fx[i] > 0) {
for (auto v : adj2[i]) {
if (v.fi == Par[i][0]) {
kq[v.se] = {mp4[{v.fi, i}].se, mp4[{v.fi, i}].fi};
}
}
}
else if (fl[i] > 0) {
for (auto v : adj2[i]) {
if (v.fi == Par[i][0]) {
kq[v.se] = {mp4[{v.fi, i}].fi, mp4[{v.fi, i}].se};
}
}
}
}
for (int i = 1; i <= m; i ++) {
if (kq[i].fi == 0 && kq[i].se == 0) {
cout << "B";
continue;
}
if (kq[i].fi == canh[i].u) {
cout << "L";
}
else {
cout << "R";
}
}
}
bool klinh;
signed main() {
memset(par, -1, sizeof(par));
ios_base::sync_with_stdio(0);
cin.tie(0);
map<pii, ll> mp3;
cin >> n >> m;
for (int i = 1; i <= m; i ++) {
cin >> canh[i].u >> canh[i].v;
canh[i].id = i;
//if (canh[i].u > canh[i].v) swap(canh[i].u, canh[i].v);
mp3[{min(canh[i].u, canh[i].v), max(canh[i].u, canh[i].v)}] ++ ;
if (mp3[{min(canh[i].u, canh[i].v), max(canh[i].u, canh[i].v)}] == 2) {
lap.push_back({canh[i].u, canh[i].v});
}
//cout << canh[i].u << " -> " << canh[i].v << endl;
adj[canh[i].u].push_back({canh[i].v, i});
adj[canh[i].v].push_back({canh[i].u, i});
}
cin >> q;
pre();
cerr << fabs(&klinh - &ghuy4g) / double(1024 * 1024);
return 0;
}
