#include <bits/stdc++.h>
using namespace std;
const int m = 1e9 + 7;
const int N = 2e5 + 69;
const int64_t INF = 100000000000000018LL;
vector<long long> v;
void printDivisors(int n) {
  for (int i = 1; i <= sqrt(n); i++) {
    if (n % i == 0) {
      if (n / i == i)
        v.push_back(i);
      else {
        v.push_back(i);
        v.push_back(n / i);
      }
    }
  }
}
void solve() {
  string s, t;
  cin >> s >> t;
  vector<vector<long long>> dp(69, vector<long long>(69, INT_MAX));
  long long n, i, j, k, sum = 0;
  cin >> n;
  for (i = 0; i < n; i++) {
    char x, y;
    long long w;
    cin >> x >> y >> w;
    dp[x - 'a'][y - 'a'] = min(dp[x - 'a'][y - 'a'], w);
  }
  if ((long long)s.size() != (long long)t.size()) {
    cout << -1;
    return;
  }
  for (i = 0; i < 26; i++) dp[i][i] = 0;
  for (k = 0; k < 26; k++) {
    for (i = 0; i < 26; i++) {
      for (j = 0; j < 26; j++) {
        dp[i][j] = min(dp[i][j], dp[i][k] + dp[k][j]);
      }
    }
  }
  long long add;
  string s1;
  for (i = 0; i < (long long)s.size(); i++) {
    if (s[i] == t[i])
      s1 += s[i];
    else {
      long long val = INT_MAX;
      val = dp[s[i] - 'a'][t[i] - 'a'];
      add = t[i] - 'a';
      if (val > dp[t[i] - 'a'][s[i] - 'a']) {
        val = dp[t[i] - 'a'][s[i] - 'a'];
        add = s[i] - 'a';
      }
      for (long long i1 = 0; i1 < 26; i1++) {
        if (dp[s[i] - 'a'][i1] + dp[t[i] - 'a'][i1] < val) {
          val = dp[s[i] - 'a'][i1] + dp[t[i] - 'a'][i1];
          add = i1;
        }
      }
      if (val == INT_MAX) {
        cout << -1;
        return;
      }
      sum += val;
      s1 += add + 'a';
    }
  }
  cout << sum << "\n";
  cout << s1;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) {
    solve();
  }
}
