#include <bits/stdc++.h>
using namespace std;
const int maxn = 3e5 + 5;
const int inf = 0x3f3f3f3f;
const int mod = 1e9 + 7;
int con[26][26];
char str1[maxn];
char str2[maxn];
char strans[maxn];
int main() {
  scanf("%s%s", str1, str2);
  memset(con, inf, sizeof(con));
  for (int i = 0; i < 26; i++) con[i][i] = 0;
  int n;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    getchar();
    char a, b;
    int w;
    scanf("%c %c %d", &a, &b, &w);
    int num1 = a - 'a';
    int num2 = b - 'a';
    if (num1 == num2) continue;
    con[num1][num2] = min(w, con[num1][num2]);
  }
  for (int k = 0; k < 26; k++) {
    for (int i = 0; i < 26; i++)
      for (int j = 0; j < 26; j++) {
        con[i][j] = min(con[i][k] + con[k][j], con[i][j]);
      }
  }
  int len = strlen(str1);
  int len1 = strlen(str2);
  if (len != len1) {
    printf("-1\n");
    return 0;
  }
  int ans = 0;
  int ff = 1;
  for (int i = 0; i < len; i++) {
    int sum1 = inf;
    int num1 = str1[i] - 'a';
    int num2 = str2[i] - 'a';
    for (int j = 0; j < 26; j++) {
      if (con[num1][j] + con[num2][j] < sum1) {
        sum1 = con[num1][j] + con[num2][j];
        strans[i] = 'a' + j;
      }
    }
    if (sum1 >= inf) {
      ff = 0;
      break;
    }
    ans += sum1;
  }
  strans[len] = '\n';
  if (ff == 0)
    printf("-1\n");
  else {
    printf("%d\n", ans);
    printf("%s\n", strans);
  }
  return 0;
}
