#include <bits/stdc++.h>
using namespace std;
const long long int inf = 1e18;
const long long int mod = 1e9 + 7;
inline long long int add(long long int x, long long int y) {
  x += y;
  if (x >= mod) x -= mod;
  return x;
}
inline long long int sub(long long int x, long long int y) {
  x -= y;
  if (x < 0) x += mod;
  return x;
}
inline long long int mul(long long int x, long long int y) {
  return ((x % mod) * (y % mod)) % mod;
}
inline long long int gcd(long long int x, long long int y) {
  return x == 0 ? y : gcd(y % x, x);
}
inline long long int power(long long int a, long long int b) {
  long long int x = 1;
  while (b) {
    if (b & 1) x = mul(x, a);
    a = mul(a, a);
    b >>= 1;
  }
  return x;
}
inline long long int inv(long long int a) { return power(a, mod - 2); }
const int MAX = 100005;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  string s, t;
  cin >> s >> t;
  int lens = s.length(), lent = t.length();
  if (lens != lent) {
    cout << -1 << "\n";
    return 0;
  }
  vector<vector<int> > d(26, vector<int>(26, MAX));
  for (int i = 0; i < 26; i++) d[i][i] = 0;
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    char from, to;
    cin >> from >> to;
    int w;
    cin >> w;
    d[from - 'a'][to - 'a'] = min(w, d[from - 'a'][to - 'a']);
  }
  for (int k = 0; k < 26; k++) {
    for (int i = 0; i < 26; i++) {
      for (int j = 0; j < 26; j++) {
        d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
      }
    }
  }
  int ans = 0;
  vector<char> str(lens);
  for (int i = 0; i < lens; i++) {
    int u = s[i] - 'a', v = t[i] - 'a';
    int val = MAX;
    for (int j = 0; j < 26; j++) {
      int value = d[u][j] + d[v][j];
      if (value < val) {
        str[i] = char('a' + j);
        val = value;
      }
    }
    if (val == MAX) {
      cout << -1 << "\n";
      return 0;
    }
    ans += val;
  }
  cout << ans << "\n";
  for (char c : str) cout << c;
  cout << "\n";
  return 0;
}
