#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_M 20

long binomial[MAX_M+1][MAX_M+1];

void build_binomial(int m)
{
  int i, j;

  binomial[0][0] = 1;
  for (i = 1; i <= m; i++) {
    binomial[i][0] = binomial[i][i] = 1;
    for (j = 1; j <= i-1; j++) {
      binomial[i][j] = binomial[i-1][j] + binomial[i-1][j-1];
    }
  }
}

void calc_children(char *pre, int start, int len, int *descendants, 
   int *children)
{
  int root = pre[start];
  int i, subtree_len;

  children[root] = 0;
  for (i = 1; i < len; ) {
    children[root]++;
    subtree_len = 1 + descendants[pre[start+i]];
    calc_children(pre, start+i, subtree_len, descendants, children);
    i += subtree_len;
  }
}

int main(void)
{
  int m;
  char pre[27], post[27];
  char pre_cmp[256][256], post_cmp[256][256];
  int descendants[256], children[256];
  int i, j, len;
  long ans;

  while (scanf("%d", &m) == 1 && m) {
    scanf("%s %s", pre, post);

    build_binomial(m);
    for (i = 0; i < 256; i++) {
      memset(pre_cmp[i], 0, 256);
      memset(post_cmp[i], 0, 256);
    }

    len = strlen(pre);
    for (i = 0; i < len; i++) {
      for (j = i+1; j < len; j++) {
	pre_cmp[pre[i]][pre[j]] = 1;
	post_cmp[post[i]][post[j]] = 1;
      }
    }

    for (i = 'a'; i < 'a' + len; i++) {
      descendants[i] = 0;
      for (j = 'a'; j < 'a' + len; j++) {
	if (pre_cmp[i][j] && post_cmp[j][i]) {
	  descendants[i]++;
	}
      }
    }

    calc_children(pre, 0, len, descendants, children);

    ans = 1;
    for (i = 'a'; i < 'a' + len; i++) {
      ans *= binomial[m][children[i]];
    }
    printf("%ld\n", ans);
  }

  return 0;
}