#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
const ll MAXN = 1e6 + 10;
const ll MAXM = 1e6 + 10;
const ll MAXP = 1e6 + 10;
const ll MAXLOG = 30;
struct edge
{
ll u,v,idx;
edge(){};
edge(ll _u, ll _v, ll _idx)
{
u = _u;
v = _v;
idx = _idx;
}
};
struct path
{
ll u,v,l;
path(){};
path(ll _u, ll _v, ll _l)
{
u = _u;
v = _v;
l = _l;
}
};
ll n,m,p;
edge edges[MAXM];
vector < edge > adj[MAXN];
vector < edge > badj[MAXN];
vector < pair < ll, ll > > order_paths;
path paths[MAXP];
bool is_bridge[MAXM];
ll bcomp[MAXN];
char ans[MAXN];
ll lift[MAXN][MAXLOG];
bool visited[MAXN];
ll direction[MAXN];
ll depth[MAXN];
edge parent[MAXN];
ll low[MAXN];
ll tin[MAXN];
ll tim;
ll comp_cnt;
void find_bridges(ll u, ll par_edge)
{
tin[u] = low[u] = ++tim;
for(edge nb : adj[u])
{
ll v = nb.v;
ll idx = nb.idx;
if(idx == par_edge)
continue;
if(tin[v])
{
low[u] = min(low[u], tin[v]);
}
else
{
find_bridges(v, idx);
low[u] = min(low[u], low[v]);
if(tin[u] < low[v])
is_bridge[idx] = true;
}
}
}
void find_components(ll u, ll comp)
{
visited[u] = true;
bcomp[u] = comp;
for(edge nb : adj[u])
{
ll v = nb.v;
ll idx = nb.idx;
if(!visited[v] && !is_bridge[idx])
find_components(v, comp);
}
}
void dfs(ll u, ll par, ll par_edge)
{
/// cout << u << " " << par << " " << par_edge << endl;
depth[u] = depth[par] + 1;
parent[u].v = par;
parent[u].idx = par_edge;
lift[u][0] = par;
for(edge nb : badj[u])
{
ll v = nb.v;
ll idx = nb.idx;
if(v != par)
dfs(v, u, idx);
}
}
void fill_lift()
{
for(int j = 1; j < MAXLOG; j++)
{
for(int i = 1; i <= comp_cnt; i++)
{
lift[i][j] = lift[lift[i][j - 1]][j - 1];
}
}
/**
for(int j = 0; j < MAXLOG; j++)
{
for(int i = 1; i <= comp_cnt; i++)
{
cout << lift[i][j] << " ";
}
cout << endl;
}
*/
}
ll find_lca(ll u, ll v)
{
if(depth[u] < depth[v])
swap(u, v);
ll diff = depth[u] - depth[v];
for(int j = MAXLOG - 1; j >= 0; j--)
{
if(diff >= (1LL << j))
{
diff -= (1LL << j);
u = lift[u][j];
}
}
if(u == v)
return u;
for(int j = MAXLOG - 1; j >= 0; j--)
{
if(lift[u][j] != lift[v][j])
{
u = lift[u][j];
v = lift[v][j];
}
}
return lift[u][0];
}
void direct_edges(ll from, ll to, ll type)
{
if(from == to)
return;
if(direction[from] == 0)
{
direction[from] = type;
ll u = parent[from].v;
ll idx = parent[from].idx;
edge e = edges[idx];
ll bu = bcomp[e.u];
ll bv = bcomp[e.v];
if(type == 1)
{
if(bu == from && bv == u)
ans[idx] = 'R';
else
ans[idx] = 'L';
}
else if(type == 2)
{
if(bu == u && bv == from)
ans[idx] = 'R';
else
ans[idx] = 'L';
}
else
{
assert(false);
}
direct_edges(u, to, type);
}
else
{
if(direction[from] != type)
{
cout << "IMPOSSIBLE" << endl;
assert(false);
}
}
}
void read()
{
cin >> n >> m;
for(int i = 1; i <= m; i++)
{
ll u,v;
cin >> u >> v;
edge e = edge(u,v,i);
edges[i] = e;
adj[u].push_back(e);
swap(e.u, e.v);
adj[v].push_back(e);
}
}
void make_bridge_graph()
{
for(int i = 1; i <= n; i++)
{
if(!tin[i])
find_bridges(i, 0);
}
for(int i = 1; i <= n; i++)
{
if(!visited[i])
find_components(i, ++comp_cnt);
}
/**
for(int i = 1; i <= n; i++)
{
cout << "Vertex " << i << " is in bridge component " << bcomp[i] << endl;
}
*/
for(edge e : edges)
{
ll u = e.u;
ll v = e.v;
ll idx = e.idx;
if(!is_bridge[e.idx])
continue;
ll bu = bcomp[u];
ll bv = bcomp[v];
badj[bu].push_back(edge(bu, bv, idx));
badj[bv].push_back(edge(bv, bu, idx));
}
/**
for(int i = 1; i <= comp_cnt; i++)
{
cout << "Neighbours of " << i << " are : " << endl;
for(edge nb : badj[i])
{
cout << " - " << nb.v << endl;
}
}
*/
}
void make_lift()
{
for(int i = 1; i <= comp_cnt; i++)
{
if(!depth[i])
{
dfs(i, 0, 0);
}
}
/*
for(int i = 1; i <= comp_cnt; i++)
{
cout << "Depth of bridge component " << i << " is " << depth[i] << endl;
}
*/
fill_lift();
}
void init_ans()
{
for(int i = 1; i <= m; i++)
{
ans[i] = 'B';
}
}
void process_paths()
{
cin >> p;
for(int i = 1; i <= p; i++)
{
ll u,v;
cin >> u >> v;
u = bcomp[u];
v = bcomp[v];
ll l = find_lca(u,v);
paths[i] = path(u, v, l);
order_paths.push_back(make_pair(depth[l], i));
}
}
void solve()
{
sort(order_paths.begin(), order_paths.end());
for(pair < ll, ll > cur_path : order_paths)
{
ll idx = cur_path.second;
ll u = paths[idx].u;
ll v = paths[idx].v;
ll l = paths[idx].l;
direct_edges(u, l, 1);
direct_edges(v, l, 2);
}
}
void print()
{
for(int i = 1; i <= m; i++)
{
cout << ans[i];
}
cout << endl;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
read();
make_bridge_graph();
make_lift();
init_ans();
process_paths();
solve();
print();
return 0;
}
