#include <bits/stdc++.h>
using namespace std;
const int inf = 19999999;
string s1, s2;
int mat[50][50];
void floyd() {
  int n = 'z' - 'a';
  for (int i = 0; i <= n; i++) {
    for (int j = 0; j <= n; j++) {
      for (int z = 0; z <= n; z++) {
        if (mat[j][z] > mat[j][i] + mat[i][z]) {
          mat[j][z] = mat[j][i] + mat[i][z];
        }
      }
    }
  }
}
int main() {
  for (int i = 0; i < 50; i++)
    for (int j = 0; j < 50; j++) mat[i][j] = inf;
  for (int i = 0; i < 50; i++) mat[i][i] = 0;
  cin >> s1 >> s2;
  int m;
  cin >> m;
  char aa[2], bb[2];
  int co;
  for (int i = 1; i <= m; i++) {
    cin >> aa >> bb >> co;
    mat[aa[0] - 'a'][bb[0] - 'a'] = min(mat[aa[0] - 'a'][bb[0] - 'a'], co);
  }
  floyd();
  int cost = 0;
  int len1 = s1.length();
  int len2 = s2.length();
  string ss;
  ss.clear();
  if (len1 != len2) {
    cout << -1 << endl;
    return 0;
  }
  int isok = 1;
  for (int i = 0; i < len1; i++) {
    int minf = inf;
    int a = s1[i] - 'a';
    int b = s2[i] - 'a';
    int qq = -1;
    for (int j = 0; j <= 'z' - 'a'; j++) {
      if (mat[a][j] + mat[b][j] < minf) {
        minf = mat[a][j] + mat[b][j];
        qq = j;
      }
    }
    if (qq == -1) {
      isok = 0;
      break;
    }
    ss += ('a' + qq);
    cost += minf;
  }
  if (isok) {
    cout << cost << endl;
    cout << ss << endl;
  } else {
    cout << -1 << endl;
  }
  return 0;
}
