#include <bits/stdc++.h>
using namespace std;
const int M = 100005;
const int N = 26;
const int inf = 0x3f3f3f3f;
int d[N][N];
char a[M], b[M];
void floyd() {
  for (int k = 0; k < N; k++) {
    for (int i = 0; i < N; i++) {
      for (int j = 0; j < N; j++) {
        d[i][j] = min(d[i][k] + d[k][j], d[i][j]);
      }
    }
  }
}
int main() {
  int n;
  scanf("%s%s", a, b);
  scanf("%d", &n);
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < N; j++) {
      if (i == j)
        d[i][j] = 0;
      else
        d[i][j] = inf;
    }
  }
  char x[2], y[2];
  int v;
  for (int i = 0; i < n; i++) {
    scanf("%s %s %d", x, y, &v);
    d[x[0] - 'a'][y[0] - 'a'] = min(d[x[0] - 'a'][y[0] - 'a'], v);
  }
  int len1 = strlen(a);
  int len2 = strlen(b);
  if (len1 != len2) {
    puts("-1");
    return 0;
  }
  floyd();
  long long ans = 0;
  for (int i = 0; i < len1; i++) {
    if (a[i] != b[i]) {
      int tmp = 0;
      for (int j = 1; j < N; j++) {
        if (d[a[i] - 'a'][j] + d[b[i] - 'a'][j] <
            d[a[i] - 'a'][tmp] + d[b[i] - 'a'][tmp])
          tmp = j;
      }
      ans += d[b[i] - 'a'][tmp] + d[a[i] - 'a'][tmp];
      a[i] = 'a' + tmp;
    }
  }
  if (ans >= inf)
    puts("-1");
  else
    printf("%I64d\n%s\n", ans, a);
  return 0;
}
