#include <bits/stdc++.h>
using namespace std;
namespace mcmf {
const int MAX = 1000010;
const long long INF = 1LL << 60;
long long cap[MAX], flow[MAX], cost[MAX], dis[MAX];
int n, m, s, t, Q[10000010], adj[MAX], link[MAX], last[MAX], from[MAX],
    visited[MAX];
void init(int nodes, int source, int sink) {
  m = 0, n = nodes, s = source, t = sink;
  for (int i = 0; i <= n; i++) last[i] = -1;
}
int addEdge(int u, int v, long long c, long long w) {
  adj[m] = v, cap[m] = c, flow[m] = 0, cost[m] = +w, link[m] = last[u],
  last[u] = m++;
  adj[m] = u, cap[m] = 0, flow[m] = 0, cost[m] = -w, link[m] = last[v],
  last[v] = m++;
  return m - 2;
}
bool spfa() {
  int i, j, x, f = 0, l = 0;
  for (i = 0; i <= n; i++) visited[i] = 0, dis[i] = INF;
  dis[s] = 0, Q[l++] = s;
  while (f < l) {
    i = Q[f++];
    for (j = last[i]; j != -1; j = link[j]) {
      if (flow[j] < cap[j]) {
        x = adj[j];
        if (dis[x] > dis[i] + cost[j]) {
          dis[x] = dis[i] + cost[j], from[x] = j;
          if (!visited[x]) {
            visited[x] = 1;
            if (f && rand() & 7)
              Q[--f] = x;
            else
              Q[l++] = x;
          }
        }
      }
    }
    visited[i] = 0;
  }
  return (dis[t] != INF);
}
pair<long long, long long> solve() {
  int i, j;
  long long mincost = 0, maxflow = 0;
  while (spfa()) {
    long long aug = INF;
    for (i = t, j = from[i]; i != s; i = adj[j ^ 1], j = from[i]) {
      aug = min(aug, cap[j] - flow[j]);
    }
    for (i = t, j = from[i]; i != s; i = adj[j ^ 1], j = from[i]) {
      flow[j] += aug, flow[j ^ 1] -= aug;
    }
    maxflow += aug, mincost += aug * dis[t];
  }
  return make_pair(mincost, maxflow);
}
}  // namespace mcmf
const long long INF = 1e9;
const int N = 205;
int id[N], revid[N];
int main() {
  int n1, n2, m, r, b;
  cin >> n1 >> n2 >> m >> r >> b;
  int source = 0, sink = n1 + n2 + 1, finalsink = n1 + n2 + 2;
  mcmf::init(n1 + n2 + 3, source, finalsink);
  int cnt = 0;
  for (int i = 1; i <= n1; i++) {
    char c;
    cin >> c;
    if (c == 'R') {
      mcmf::addEdge(source, i, 1, -INF);
      mcmf::addEdge(source, i, INF, 0);
      ++cnt;
    }
    if (c == 'B') {
      mcmf::addEdge(i, sink, 1, -INF);
      mcmf::addEdge(i, sink, INF, 0);
      ++cnt;
    }
    if (c == 'U') {
      mcmf::addEdge(source, i, INF, 0);
      mcmf::addEdge(i, sink, INF, 0);
    }
  }
  for (int i = 1; i <= n2; i++) {
    char c;
    cin >> c;
    if (c == 'B') {
      mcmf::addEdge(source, n1 + i, 1, -INF);
      mcmf::addEdge(source, n1 + i, INF, 0);
      ++cnt;
    }
    if (c == 'R') {
      mcmf::addEdge(n1 + i, sink, 1, -INF);
      mcmf::addEdge(n1 + i, sink, INF, 0);
      ++cnt;
    }
    if (c == 'U') {
      mcmf::addEdge(source, n1 + i, INF, 0);
      mcmf::addEdge(n1 + i, sink, INF, 0);
    }
  }
  for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    id[i] = mcmf::addEdge(u, n1 + v, 1, r);
    revid[i] = mcmf::addEdge(n1 + v, u, 1, b);
  }
  mcmf::addEdge(sink, finalsink, m, 0);
  mcmf::addEdge(source, sink, m, 0);
  long long ans = mcmf::solve().first + cnt * INF;
  if (ans >= INF) {
    cout << -1 << endl;
    return 0;
  }
  cout << ans << endl;
  for (int i = 0; i < m; i++) {
    if (mcmf::flow[id[i]])
      cout << "R";
    else if (mcmf::flow[revid[i]])
      cout << "B";
    else
      cout << "U";
  }
}
