#include <bits/stdc++.h>
using namespace std;
const long double PI = 3.1415926535897932384626433832795029L;
vector<vector<vector<bool> > > precalc(
    string &str, vector<vector<pair<int, int> > > &moves) {
  int n = (int)str.size(), m = (int)moves.size();
  vector<vector<vector<bool> > > can(n,
                                     vector<vector<bool> >(n, vector<bool>(m)));
  for (int i = 0; i < n; i++) can[i][i][str[i]] = true;
  for (int delta = 1; delta < n; delta++)
    for (int i = 0, j = delta; j < n; i++, j++)
      for (int k = 0; k < m; k++)
        for (int l = 0; l < (int)moves[k].size(); l++)
          for (int d = 0; d < delta; d++)
            if (can[i][i + d][moves[k][l].first] &&
                can[i + d + 1][j][moves[k][l].second])
              can[i][j][k] = true;
  return can;
}
void debug(vector<vector<vector<bool> > > &vet) {
  for (int i = 0; i < (int)vet.size(); i++)
    for (int j = 0; j < (int)vet[i].size(); j++)
      for (int k = 0; k < (int)vet[i][j].size(); k++)
        if (vet[i][j][k]) printf("%d %d %d\n", i, j, k);
  printf("##########\n");
}
bool solve(int testNumber) {
  const int N = 26;
  string A, B;
  vector<vector<pair<int, int> > > vet(N, vector<pair<int, int> >());
  if (!(cin >> A >> B)) return false;
  int na = (int)A.size(), nb = (int)B.size();
  for (int i = 0; i < na; i++) A[i] -= 'a';
  for (int i = 0; i < nb; i++) B[i] -= 'a';
  int n;
  cin >> n;
  while (n--) {
    string str;
    cin >> str;
    vet[str[0] - 'a'].push_back(make_pair(str[3] - 'a', str[4] - 'a'));
  }
  vector<vector<vector<bool> > > canA = precalc(A, vet), canB = precalc(B, vet);
  const int INF = 100;
  vector<vector<int> > dp(na + 1, vector<int>(nb + 1, INF));
  dp[0][0] = 0;
  for (int i = 1; i <= na; i++)
    for (int j = 1; j <= nb; j++)
      for (int k = 0; k < i; k++)
        for (int l = 0; l < j; l++)
          for (int m = 0; m < N; m++)
            if (canA[k][i - 1][m] and canB[l][j - 1][m])
              dp[i][j] = min(dp[i][j], dp[k][l] + 1);
  printf("%d\n", dp[na][nb] < INF ? dp[na][nb] : -1);
  return true;
}
int main() {
  for (int i = 1; solve(i); i++)
    ;
  return 0;
}
