#include <bits/stdc++.h>
using namespace std;
const long long INF = 0x3f3f3f3f;
const long long mod = 1000000007;
const long double eps = 1e-14;
int i, j;
string s, t;
int n;
long long dis[30][30];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> s >> t;
  cin >> n;
  for (int i = 0; i < 26; i++)
    for (int j = 0; j < 26; j++) dis[i][j] = INF;
  for (int i = 0; i < 26; i++) dis[i][i] = 0;
  for (int i = 0; i < n; i++) {
    char c, d;
    long long x;
    cin >> c >> d >> x;
    dis[c - 'a'][d - 'a'] = min(x, dis[c - 'a'][d - 'a']);
  }
  if (s.size() != t.size()) return cout << -1 << endl, 0;
  for (int k = 0; k < 26; k++) {
    for (int i = 0; i < 26; i++) {
      for (int j = 0; j < 26; j++) {
        dis[i][j] = min(dis[i][j], dis[i][k] + dis[k][j]);
      }
    }
  }
  long long ans = 0;
  string out;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == t[i]) {
      out.push_back(s[i]);
      continue;
    }
    int a1 = s[i] - 'a', a2 = t[i] - 'a';
    long long cnt = 1e10;
    char ch = '~';
    for (int j = 0; j < 26; j++) {
      if (dis[a1][j] == INF || dis[a2][j] == INF) continue;
      if (dis[a1][j] + dis[a2][j] < cnt) {
        cnt = dis[a1][j] + dis[a2][j];
        ch = 'a' + j;
      }
    }
    if (ch == '~') return cout << -1 << endl, 0;
    ans += cnt;
    out.push_back(ch);
  }
  cout << ans << endl << out << endl;
  return 0;
}
