#include <bits/stdc++.h>
using namespace std;
const int inf = 0x3f3f3f3f;
struct Edge {
  int to, val, next, cost;
} edge[300086];
int s, t;
int cnt = -1;
int head[300086];
queue<int> q;
int d[300086];
int cur[300086];
int inq[300086];
int vis[300086];
int costsum;
void addEdge(int u, int v, int w, int f) {
  cnt++;
  edge[cnt].to = v;
  edge[cnt].val = w;
  edge[cnt].next = head[u];
  edge[cnt].cost = f;
  head[u] = cnt;
  cnt++;
  edge[cnt].to = u;
  edge[cnt].val = 0;
  edge[cnt].next = head[v];
  edge[cnt].cost = -f;
  head[v] = cnt;
}
bool bfs() {
  memset(d, 0x3f, sizeof(d));
  memset(vis, 0, sizeof(vis));
  d[s] = 0;
  q.push(s);
  inq[s] = 1;
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    inq[u] = 0;
    for (int i = head[u]; i != -1; i = edge[i].next) {
      int v = edge[i].to;
      cur[v] = head[v];
      int f = edge[i].cost;
      if (d[v] > d[u] + f && edge[i].val > 0) {
        d[v] = d[u] + f;
        if (!inq[v]) {
          q.push(v);
          inq[v] = 1;
        }
      }
    }
  }
  return d[t] != inf;
}
int dfs(int u, int flow) {
  vis[u] = 1;
  int nowflow = 0;
  if (u == t) return flow;
  for (int i = cur[u]; i != -1; i = edge[i].next) {
    cur[u] = i;
    int v = edge[i].to;
    int w = edge[i].val;
    int f = edge[i].cost;
    if (d[v] == d[u] + f && w > 0 && !vis[v]) {
      int k = dfs(v, min(flow - nowflow, w));
      if (k > 0) {
        edge[i].val -= k;
        edge[i ^ 1].val += k;
        nowflow += k;
        costsum += f * k;
        if (nowflow == flow) break;
      }
    }
  }
  vis[u] = 0;
  if (!nowflow) d[u] = inf;
  return nowflow;
}
int dinic() {
  int ans = 0;
  while (bfs()) {
    ans += dfs(s, inf);
  }
  return ans;
}
int n1, n2, m, r, b;
int x, y;
int val[300086];
int id[300086];
char S[300086];
int sum;
int main() {
  memset(head, -1, sizeof(head));
  scanf("%d%d%d%d%d", &n1, &n2, &m, &r, &b);
  s = n1 + n2 + 1, t = n1 + n2 + 2;
  scanf("%s", S + 1);
  for (int i = 1; i <= n1; i++) {
    if (S[i] == 'B') {
      addEdge(i, t, inf, 0), val[i]--, val[t]++;
    } else if (S[i] == 'R') {
      addEdge(s, i, inf, 0), val[s]--, val[i]++;
    } else {
      addEdge(s, i, inf, 0), addEdge(i, t, inf, 0);
    }
  }
  scanf("%s", S + 1);
  for (int i = 1; i <= n2; i++) {
    if (S[i] == 'R') {
      addEdge(i + n1, t, inf, 0), val[i + n1]--, val[t]++;
    } else if (S[i] == 'B') {
      addEdge(s, i + n1, inf, 0), val[s]--, val[i + n1]++;
    } else {
      addEdge(s, i + n1, inf, 0), addEdge(i + n1, t, inf, 0);
    }
  }
  for (int i = 1; i <= m; i++) {
    scanf("%d%d", &x, &y);
    addEdge(x, y + n1, 1, r), addEdge(y + n1, x, 1, b);
    id[i] = cnt;
  }
  addEdge(t, s, inf, 0);
  s += 2, t += 2;
  for (int i = 1; i <= n1 + n2 + 2; i++) {
    if (val[i] > 0)
      addEdge(s, i, val[i], 0), sum += val[i];
    else if (val[i] < 0)
      addEdge(i, t, -val[i], 0);
  }
  if (dinic() != sum) return printf("-1"), 0;
  printf("%d\n", costsum);
  for (int i = 1; i <= m; i++) {
    if (edge[id[i]].val)
      printf("B");
    else if (edge[id[i] - 2].val)
      printf("R");
    else
      printf("U");
  }
}
