#include <bits/stdc++.h>
using namespace std;
int main() {
  string s, t;
  cin >> s >> t;
  if (s.length() != t.length()) {
    cout << -1 << endl;
    return 0;
  }
  int n;
  cin >> n;
  map<char, map<char, int> > m;
  for (char c = 'a'; c <= 'z'; c++) m[c][c] = 0;
  for (int i = 0; i < n; i++) {
    char f, t;
    cin >> f >> t;
    int c;
    cin >> c;
    if (m[f].count(t))
      m[f][t] = min(m[f][t], c);
    else
      m[f][t] = c;
  }
  for (char k = 'a'; k <= 'z'; k++) {
    for (char i = 'a'; i <= 'z'; i++) {
      for (char j = 'a'; j <= 'z'; j++) {
        if (m[i].count(k) && m[k].count(j)) {
          if (m[i].count(j)) {
            m[i][j] = min(m[i][j], m[i][k] + m[k][j]);
          } else {
            m[i][j] = m[i][k] + m[k][j];
          }
        }
      }
    }
  }
  int ret = 0;
  string ans;
  for (int i = 0; i < s.length(); i++) {
    char a = s[i], c = t[i];
    int minc = -1;
    char minb;
    for (char b = 'a'; b <= 'z'; b++) {
      if (m[a].count(b) && m[c].count(b)) {
        int tmp = m[a][b] + m[c][b];
        if (minc < 0 || tmp < minc) {
          minc = tmp;
          minb = b;
        }
      }
    }
    if (minc < 0) {
      cout << -1 << endl;
      return 0;
    }
    ret += minc;
    ans += minb;
  }
  cout << ret << endl;
  cout << ans << endl;
  return 0;
}
