#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void si(T &x) {
  register int c = getchar();
  x = 0;
  int neg = 0;
  for (; ((c<48 | c> 57) && c != '-'); c = getchar())
    ;
  if (c == '-') {
    neg = 1;
    c = getchar();
  }
  for (; c > 47 && c < 58; c = getchar()) {
    x = (x << 1) + (x << 3) + c - 48;
  }
  if (neg) x = -x;
}
template <class T>
inline T bigmod(T p, T e, T M) {
  long long ret = 1;
  for (; e > 0; e >>= 1) {
    if (e & 1) ret = (ret * p) % M;
    p = (p * p) % M;
  }
  return (T)ret;
}
template <class T>
inline T gcd(T a, T b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
template <class T>
inline T modinverse(T a, T M) {
  return bigmod(a, M - 2, M);
}
void io() {
  freopen("in.txt", "r", stdin);
  freopen("out.txt", "w", stdout);
}
const int N = 30;
int A[N][N];
string s, t;
int main() {
  int n;
  cin >> s >> t;
  cin >> n;
  for (int i = 0; i < 26; i++)
    for (int j = 0; j < 26; j++) A[i][j] = 1 << 29;
  for (int i = 0; i < 26; i++) A[i][i] = 0;
  for (int i = 0; i < n; i++) {
    char c1, c2;
    int w;
    scanf(" %c %c %d", &c1, &c2, &w);
    c1 -= 'a', c2 -= 'a';
    A[c1][c2] = ((A[c1][c2]) > (w) ? (w) : (A[c1][c2]));
  }
  if (s.length() != t.length()) {
    puts("-1");
    return 0;
  }
  for (int k = 0; k < 26; k++)
    for (int i = 0; i < 26; i++)
      for (int j = 0; j < 26; j++) {
        A[i][j] =
            ((A[i][j]) > (A[i][k] + A[k][j]) ? (A[i][k] + A[k][j]) : (A[i][j]));
      }
  int cost = 0, foo = 1;
  string res;
  for (int i = 0; i < s.size(); i++) {
    int c1 = s[i] - 'a', c2 = t[i] - 'a';
    int oo = 1 << 29;
    char cc = -1;
    for (int k = 0; k < 26; k++) {
      int o = A[c1][k] + A[c2][k];
      if (o < oo) {
        oo = o;
        cc = k;
      }
    }
    if (oo == 1 << 29) {
      foo = 0;
      break;
    }
    cost += oo;
    res.push_back((cc + 'a'));
  }
  if (foo) {
    printf("%d\n", cost);
    cout << res << endl;
  } else
    printf("-1\n");
  return 0;
}
