#include <bits/stdc++.h>
using namespace std;
const int MAXN = 55, MAXS = 29;
bool f1[MAXN][MAXN][MAXS], f2[MAXN][MAXN][MAXS];
int dp[MAXN][MAXN];
int a[MAXN], b[MAXN];
int trs[MAXN][3];
int n, m, tn;
int main() {
  char t[MAXN];
  scanf("%s", t + 1);
  n = strlen(t + 1);
  for (int i = 1; i <= n; i++) a[i] = t[i] - 'a' + 1;
  scanf("%s", t + 1);
  m = strlen(t + 1);
  for (int i = 1; i <= m; i++) b[i] = t[i] - 'a' + 1;
  scanf("%d", &tn);
  for (int i = 1; i <= tn; i++) {
    scanf("%s", t);
    trs[i][0] = t[0] - 'a' + 1;
    trs[i][1] = t[3] - 'a' + 1;
    trs[i][2] = t[4] - 'a' + 1;
  }
  for (int i = 1; i <= n; i++) f1[i][i][a[i]] = true;
  for (int d = 1; d < n; d++)
    for (int i = 1; i + d <= n; i++)
      for (int j = i; j < i + d; j++)
        for (int k = 1; k <= tn; k++)
          if (f1[i][j][trs[k][1]] && f1[j + 1][i + d][trs[k][2]])
            f1[i][i + d][trs[k][0]] = true;
  for (int i = 1; i <= m; i++) f2[i][i][b[i]] = true;
  for (int d = 1; d < m; d++)
    for (int i = 1; i + d <= m; i++)
      for (int j = i; j < i + d; j++)
        for (int k = 1; k <= tn; k++)
          if (f2[i][j][trs[k][1]] && f2[j + 1][i + d][trs[k][2]])
            f2[i][i + d][trs[k][0]] = true;
  memset(dp, 10, sizeof(dp));
  dp[0][0] = 0;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++) {
      for (int ii = 0; ii < i; ii++)
        for (int jj = 0; jj < j; jj++)
          if (dp[ii][jj] + 1 < dp[i][j]) {
            for (int k = 1; k <= 26; k++)
              if (f1[ii + 1][i][k] && f2[jj + 1][j][k])
                dp[i][j] = dp[ii][jj] + 1;
          }
    }
  if (dp[n][m] > 1000)
    printf("-1\n");
  else
    printf("%d\n", dp[n][m]);
  return 0;
}
