#include <bits/stdc++.h>
using namespace std;
string str1;
string str2;
string restr;
long long int cost[27][27];
int main() {
  long long int i, j, k, t, n, m, n1, n2;
  cin >> str1;
  cin >> str2;
  char c1, c2;
  long long int wt;
  cin >> n;
  for (i = 0; i <= 26; i++) {
    for (j = 0; j <= 26; j++) {
      cost[i][j] = 1123456789LL * 1123456789LL;
    }
  }
  for (i = 0; i < n; i++) {
    cin >> c1 >> c2 >> wt;
    cost[c1 - 96][c2 - 96] = min(cost[c1 - 96][c2 - 96], wt);
  }
  n1 = str1.length();
  n2 = str2.length();
  if (n1 != n2) {
    printf("-1\n");
    return 0;
  }
  long long int t1, t2, t3, t4;
  for (k = 1; k <= 26; k++) {
    for (i = 1; i <= 26; i++) {
      for (j = 1; j <= 26; j++) {
        cost[i][j] = min(cost[i][k] + cost[k][j], cost[i][j]);
      }
    }
  }
  long long int ans = 0, tmp, tans;
  char tc;
  restr = "";
  for (i = 0; i < n1; i++) {
    if (str1[i] != str2[i]) {
      if (cost[str1[i] - 96][str2[i] - 96] > cost[str2[i] - 96][str1[i] - 96]) {
        tmp = cost[str2[i] - 96][str1[i] - 96];
        tc = str1[i];
        tans = tmp;
      } else {
        tmp = cost[str1[i] - 96][str2[i] - 96];
        tc = str2[i];
        tans = tmp;
      }
      for (k = 1; k <= 26; k++) {
        if (cost[str1[i] - 96][k] + cost[str2[i] - 96][k] < tmp) {
          tc = k + 96;
          tans = cost[str1[i] - 96][k] + cost[str2[i] - 96][k];
          tmp = tans;
        }
      }
      if (tmp == 1123456789LL * 1123456789LL) {
        printf("-1");
        return 0;
      }
      restr = restr + tc;
      ans += tans;
    } else {
      restr = restr + str1[i];
    }
  }
  if (ans >= 1123456789LL * 1123456789LL) {
    printf("-1");
    return 0;
  }
  cout << ans << endl;
  cout << restr;
  return 0;
}
