#include <bits/stdc++.h>
using namespace std;
int n, c, res, a[26][26];
char c1, c2;
string s1, s2;
int main() {
  cin >> s1 >> s2 >> n;
  for (int(i) = 0; (i) < (26); ++(i))
    for (int(j) = 0; (j) < (26); ++(j))
      if (i == j)
        a[i][j] = 0;
      else
        a[i][j] = 10000;
  for (int(i) = 0; (i) < (n); ++(i)) {
    cin >> c1 >> c2 >> c;
    a[c1 - 'a'][c2 - 'a'] = min(a[c1 - 'a'][c2 - 'a'], c);
  }
  for (int(k) = 0; (k) < (26); ++(k))
    for (int(i) = 0; (i) < (26); ++(i))
      for (int(j) = 0; (j) < (26); ++(j))
        a[i][j] = min(a[i][j], a[i][k] + a[k][j]);
  if (s1.size() != s2.size()) {
    cout << -1 << endl;
    return 0;
  }
  for (int(i) = 0; (i) < (s1.size()); ++(i)) {
    int w = 10000, ver = -1;
    for (int(j) = 0; (j) < (26); ++(j)) {
      if (a[s1[i] - 'a'][j] < 10000 && a[s2[i] - 'a'][j] < 10000) {
        if (w > a[s1[i] - 'a'][j] + a[s2[i] - 'a'][j]) {
          ver = j;
          w = a[s1[i] - 'a'][j] + a[s2[i] - 'a'][j];
        }
      }
    }
    if (ver != -1) {
      s1[i] = s2[i] = (char)('a' + ver);
      res += w;
    } else {
      cout << -1 << endl;
      return 0;
    }
  }
  cout << res << endl << s1 << endl;
  return 0;
}
