#include <bits/stdc++.h>
using namespace std;
long long mask1[54][54], mask2[54][54], w1[54], w2[54], w3[54];
int dp[54][54];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  string a, b;
  cin >> a >> b;
  for (int i = 1; i <= a.length(); i++) mask1[i][i] |= 1LL << (a[i - 1] - 'a');
  for (int i = 1; i <= b.length(); i++) mask2[i][i] |= 1LL << (b[i - 1] - 'a');
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    string q;
    cin >> q;
    w1[i] |= 1LL << (q[0] - 'a');
    w2[i] |= 1LL << (q[3] - 'a');
    w3[i] |= 1LL << (q[4] - 'a');
  }
  for (int len = 1; len <= a.length(); len++) {
    for (int st = 1; st <= a.length(); st++) {
      int en = st + len;
      for (int mid = st; mid < en; mid++) {
        for (int s = 1; s <= n; s++) {
          if (mask1[st][mid] & w2[s])
            if (mask1[mid + 1][en] & w3[s]) mask1[st][en] |= w1[s];
        }
      }
    }
  }
  for (int len = 1; len <= b.length(); len++) {
    for (int st = 1; st <= b.length(); st++) {
      int en = st + len;
      for (int mid = st; mid < en; mid++) {
        for (int s = 1; s <= n; s++) {
          if (mask2[st][mid] & w2[s])
            if (mask2[mid + 1][en] & w3[s]) mask2[st][en] |= w1[s];
        }
      }
    }
  }
  for (int r = 0; r < 54; r++)
    for (int u = 0; u < 54; u++) dp[r][u] = INT_MAX / 2;
  dp[0][0] = 0;
  for (int i = 1; i <= a.length(); i++) {
    for (int j = 1; j <= b.length(); j++) {
      for (int e = 1; e <= i; e++) {
        for (int r = 1; r <= j; r++) {
          if (mask1[e][i] & mask2[r][j])
            dp[i][j] = min(dp[i][j], 1 + dp[e - 1][r - 1]);
        }
      }
    }
  }
  if (dp[a.length()][b.length()] > 50)
    cout << -1 << "\n";
  else
    cout << dp[a.length()][b.length()];
}
