#include <bits/stdc++.h>
using namespace std;
const int N = 30, INF = 1e5 + 5;
int dis[N][N];
char s1[INF], s2[INF];
int main() {
  for (int i = 0; i < N; i++)
    for (int j = 0; j < N; j++)
      if (i != j) dis[i][j] = INF;
  scanf("%s %s", s1, s2);
  int n, w;
  scanf("%d", &n);
  char ch1[2], ch2[2];
  for (int i = 0; i < n; i++) {
    scanf("%s %s %d", ch1, ch2, &w);
    dis[ch1[0] - 'a'][ch2[0] - 'a'] = min(dis[ch1[0] - 'a'][ch2[0] - 'a'], w);
  }
  for (int k = 0; k < N; k++)
    for (int i = 0; i < N; i++)
      for (int j = 0; j < N; j++)
        dis[i][j] = min(dis[i][j], dis[i][k] + dis[k][j]);
  if (strlen(s1) != strlen(s2)) {
    printf("-1\n");
    return 0;
  }
  char ANS[INF];
  int ans = 0;
  for (int i = 0; s1[i]; i++) {
    int dx1 = s1[i] - 'a';
    int dx2 = s2[i] - 'a';
    int mn = INF;
    char choose;
    for (int j = 0; j < 26; j++) {
      if (dis[dx1][j] + dis[dx2][j] < mn) {
        mn = dis[dx1][j] + dis[dx2][j];
        choose = j + 'a';
      }
    }
    if (mn == INF) {
      printf("-1\n");
      return 0;
    }
    ANS[i] = choose;
    ans += mn;
  }
  ANS[strlen(s1)] = '\0';
  printf("%d\n%s\n", ans, ANS);
}
