/* Fri Mar 19 17:09:29 JST 2004 */
/* Fri Mar 19 17:37:31 JST 2004 */
#include <stdio.h>
#include <ctype.h>
#include <limits.h>

int adj[52][52];
int minp;
int p1, p2;

int ctoi(char c)
{
  if (isupper(c)) { return c-'A'; }
  if (islower(c)) { return c-'a' + 26; }
  return c/0;
}

int back(int s)
{
  return s + ((s-1) / 19) + 1;
}

void dfs(int current, int visited[52], int have)
{
  int i;
  if (current == p1) {
    if (minp > have) { minp = have; }
    return;
  }

  for (i = 0; i < 52; i++) {
    if (adj[current][i] && !visited[i]) {
      visited[i] = 1;
      if (0 <= current && current <= 25) {
        dfs(i, visited, back(have));
      }
      else {
        dfs(i, visited, have + 1);
      }
      visited[i] = 0;
    }
  }
}

int main()
{
  char s[1024];
  int i, j, n, p, visited[52];
  char c1, c2;
  int icase;

  for (icase = 1; ; icase++) {
    gets(s); n = atoi(s); if (n < 0) { break; }
    for (i = 0; i <= 52; i++) {
      for (j = 0; j <= 52; j++) {
        adj[i][j] = 0;
      }
    }
    for (i = 0; i < n; i++) {
      gets(s); sscanf(s, "%c %c", &c1, &c2); 
      adj[ctoi(c1)][ctoi(c2)] = adj[ctoi(c2)][ctoi(c1)] = 1;
    }

    gets(s); sscanf(s, "%d %c %c", &p, &c1, &c2);
    p1 = ctoi(c1); p2 = ctoi(c2);
    for (i = 0; i < 52; i++) {
      visited[i] = 0;
    }
    minp = INT_MAX;
    dfs(p2, visited, p);
    printf("Case %d: %d\n", icase, minp);
  }
  return 0;
}