#include <bits/stdc++.h>
using namespace std;
long long int mat[26][26];
string s1, s2, s3;
string c1, c2;
char ch;
long long int n, l1, l2, mcost, ans = INT_MAX;
void floyd() {
  long long int i, j, k;
  for (i = 0; i < 26; i++) {
    for (j = 0; j < 26; j++) {
      for (k = 0; k < 26; k++) {
        mat[j][k] = min(mat[j][k], mat[j][i] + mat[i][k]);
      }
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int i, j, t;
  for (i = 0; i < 26; i++) {
    for (j = 0; j < 26; j++) {
      if (i == j)
        mat[i][j] = 0;
      else
        mat[i][j] = INT_MAX;
    }
  }
  cin >> s1 >> s2;
  s3 = s1;
  l1 = s1.length();
  l2 = s2.length();
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> c1 >> c2 >> mcost;
    mat[c1.at(0) - 'a'][c2.at(0) - 'a'] =
        min(mat[c1.at(0) - 'a'][c2.at(0) - 'a'], mcost);
  }
  if (l1 == l2) {
    floyd();
    ans = 0;
    for (i = 0; i < l1; i++) {
      if (s1.at(i) == s2.at(i))
        continue;
      else {
        t = INT_MAX;
        for (j = 0; j < 26; j++) {
          if (t > mat[s1.at(i) - 'a'][j] + mat[s2.at(i) - 'a'][j]) {
            t = mat[s1.at(i) - 'a'][j] + mat[s2.at(i) - 'a'][j];
            ch = 'a' + j;
          }
        }
        ans += t;
        s3.at(i) = ch;
      }
    }
  }
  if (ans >= INT_MAX) {
    cout << -1 << endl;
  } else {
    cout << ans << endl;
    cout << s3 << endl;
  }
  return 0;
}
