#include <bits/stdc++.h>
using namespace std;
const int inf = 1e8;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  string x, y;
  cin >> x >> y;
  if (x.size() != y.size()) {
    cout << "-1\n";
    return 0;
  }
  int m;
  cin >> m;
  vector<vector<int>> d(26, vector<int>(26, inf));
  for (int i = 0; i < 26; i++) d[i][i] = 0;
  for (int i = 0; i < m; i++) {
    string su, sv;
    int w;
    cin >> su >> sv >> w;
    int u = su[0] - 'a', v = sv[0] - 'a';
    d[u][v] = min(d[u][v], w);
  }
  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]);
      }
    }
  }
  vector<vector<int>> t(26, vector<int>(26, inf));
  vector<vector<char>> ct(26, vector<char>(26));
  for (int i = 0; i < 26; i++) {
    for (int j = 0; j < 26; j++) {
      for (int k = 0; k < 26; k++) {
        if (d[i][k] == inf || d[j][k] == inf) continue;
        if (t[i][j] > d[i][k] + d[j][k]) {
          t[i][j] = d[i][k] + d[j][k];
          ct[i][j] = 'a' + k;
        }
      }
    }
  }
  string res;
  int ans = 0;
  for (int i = 0; i < x.size(); i++) {
    int u = x[i] - 'a', v = y[i] - 'a';
    int cost = t[u][v];
    if (cost == inf) {
      cout << "-1\n";
      return 0;
    }
    ans += cost;
    res.push_back(ct[u][v]);
  }
  cout << ans << "\n";
  cout << res << "\n";
  return 0;
}
