#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5; 

int n, m, q; 
vector<pair<int, int>> G[N]; 
bool bri[N]; 

int dfn[N], low[N], num, col[N], st[N], tot, cnt; 
void tarjan(int x, int in_edge) {
    dfn[x] = low[x] = ++num; st[++tot] = x; 
    for (auto [y, id] : G[x]) 
        if (!dfn[y]) {
            tarjan(y, id), low[x] = min(low[x], low[y]); 
            if (dfn[x] < low[y]) bri[id] = 1; 
        } else if (id != in_edge) low[x] = min(low[x], dfn[y]); 
    if (dfn[x] == low[x]) {
        int y; ++cnt; 
        do col[y = st[tot--]] = cnt; while (x != y); 
    }
}

vector<int> E[N]; 
bool vis[N]; 
int d[N], dep[N]; 
void dfs(int x, int ff) {
    vis[x] = 1; dep[x] = dep[ff] + 1; 
    for (int y : E[x]) if (y != ff) dfs(y, x), d[x] += d[y]; 
}

int u[N], v[N]; 

int main(void) {
    ios::sync_with_stdio(0); 
    cin >> n >> m; 
    for (int i = 1; i <= m; ++i) {
        int u, v; cin >> u >> v; ::u[i] = u, ::v[i] = v; 
        G[u].emplace_back(v, i); G[v].emplace_back(u, i); 
    }
    for (int i = 1; i <= n; ++i) if (!dfn[i]) tarjan(i, 0); 
    for (int u = 1; u <= n; ++u) for (auto [v, id] : G[u]) if (col[u] != col[v])
        E[col[u]].emplace_back(col[v]); 
    
    cin >> q; 
    while (q--) {
        int x, y; cin >> x >> y; // x -> y
        x = col[x]; y = col[y]; 
        if (x != y) ++d[x], --d[y]; 
    }
    
    for (int i = 1; i <= cnt; ++i) if (!vis[i]) dfs(i, 0); 

    for (int i = 1; i <= m; ++i)
        if (!bri[i]) cout << "B"; 
        else {
            if (dep[col[u[i]]] > dep[col[v[i]]]) {
                if (d[col[u[i]]] > 0) cout << "R";
                else if (d[col[u[i]]] == 0) cout << "B"; 
                else cout << "L"; 
            } else {
                if (d[col[v[i]]] > 0) cout << "L"; 
                else if (d[col[v[i]]] == 0) cout << "B"; 
                else cout << "R"; 
            }
        }
    cout << "\n"; 
    return 0;
}