#include <bits/stdc++.h>
using namespace std;
const int MAX = 1000000000;
int main() {
  string s, t;
  cin >> s >> t;
  if (s.size() != t.size()) {
    cout << -1;
    return 0;
  }
  int n;
  cin >> n;
  vector<char> a(n), b(n);
  vector<vector<int> > gr(26, vector<int>(26, MAX));
  vector<int> w(n);
  for (int i = 0; i < n; ++i) {
    string buf1, buf2;
    cin >> buf1 >> buf2 >> w[i];
    a[i] = buf1[0];
    b[i] = buf2[0];
    gr[a[i] - 'a'][b[i] - 'a'] = min(gr[a[i] - 'a'][b[i] - 'a'], w[i]);
  }
  for (int i = 0; i < gr.size(); ++i) gr[i][i] = 0;
  for (int k = 0; k < gr.size(); ++k)
    for (int i = 0; i < gr.size(); ++i)
      for (int j = 0; j < gr.size(); ++j)
        gr[i][j] = min(gr[i][j], gr[i][k] + gr[k][j]);
  long long sum = 0;
  string res(s.size(), 'a');
  for (int i = 0; i < t.size(); ++i) {
    int cur = MAX;
    for (int j = 0; j < gr.size(); ++j) {
      if (cur > gr[s[i] - 'a'][j] + gr[t[i] - 'a'][j]) {
        cur = gr[s[i] - 'a'][j] + gr[t[i] - 'a'][j];
        res[i] = 'a' + j;
      }
    }
    if (cur == MAX) {
      cout << -1;
      return 0;
    } else
      sum += cur;
  }
  cout << sum << endl << res << endl;
  return 0;
}
