#include <bits/stdc++.h>
using namespace std;
const long double eps = 1e-7;
const string alpha = "abcdefghijklmnopqrstuvwxyz";
int dx[8] = {+1, +1, +1, 0, 0, -1, -1, -1};
int dy[8] = {+1, 0, -1, +1, -1, +1, 0, -1};
long long power(long long x, long long y) {
  long long res = 1;
  x = x;
  while (y > 0) {
    if (y & 1) res = (res * x);
    y = y >> 1;
    x = (x * x);
  }
  return res;
}
template <typename T>
T gcd(T a, T mp) {
  if (a == 0) return mp;
  return gcd(mp % a, a);
}
template <typename T>
T powm(T a, T mp, long long m) {
  T cnt = 1;
  while (mp > 0) {
    if (mp % 2 == 1) cnt = (cnt * a) % m;
    mp /= 2;
    a = (a * a) % m;
  }
  return cnt % m;
}
long long ncr(long long n, long long r) {
  long long res = 1;
  if (r > n) return 0;
  if (r > n - r) r = n - r;
  for (long long i = 0; i < r; i++) {
    res *= (n - i);
    res /= (i + 1);
  }
  return res;
}
long long sqr(long long x) { return x * x; }
const int mod = 998244353;
const int N = 1000005;
void prec() {}
void run() {
  string s, t;
  cin >> s >> t;
  int dp[26][26];
  for (int i = 0; i <= 25; ++i) {
    for (int j = 0; j <= 25; ++j) {
      if (i == j)
        dp[i][j] = 0;
      else
        dp[i][j] = 1e7;
    }
  }
  int n, ans = 0;
  cin >> n;
  while (n--) {
    char ch1, ch2;
    int x;
    cin >> ch1 >> ch2 >> x;
    dp[ch1 - 'a'][ch2 - 'a'] = min(dp[ch1 - 'a'][ch2 - 'a'], x);
  }
  for (int i = 0; i <= 25; ++i) {
    for (int j = 0; j <= 25; ++j) {
      for (int k = 0; k <= 25; ++k) {
        if (j == k) continue;
        dp[j][k] = min(dp[j][k], dp[j][i] + dp[i][k]);
      }
    }
  }
  int l1 = (long long)s.size(), l2 = (long long)t.size();
  if (l1 != l2) {
    cout << -1;
    return;
  }
  string final = "";
  for (int i = 0; i < l1; ++i) {
    int temp = 1e9;
    char ch;
    for (int j = 0; j <= 25; ++j) {
      if ((dp[s[i] - 'a'][j] + dp[t[i] - 'a'][j]) < temp) {
        temp = dp[s[i] - 'a'][j] + dp[t[i] - 'a'][j];
        ch = 'a' + j;
      }
    }
    if (temp > 1e5) {
      cout << -1 << "\n";
      return;
    }
    final += ch;
    ans += temp;
  }
  cout << ans << "\n";
  cout << final;
}
int main() {
  cin.sync_with_stdio(0);
  cin.tie(0);
  cin.exceptions(cin.failbit);
  int tc = 1;
  prec();
  for (long long i = 0; i < tc; ++i) run();
  return 0;
}
