#include <bits/stdc++.h>
using namespace std;
char na[54][5];
char p[54][5];
int ans[54];
int main() {
  int i, j, k;
  int n, m;
  int tr;
  int cnt = 0;
  for (i = 0; i < 26; i++) {
    na[i][0] = 'A' + i;
    na[i + 26][0] = 'A' + i;
    na[i + 26][1] = 'a' + i;
  }
  scanf("%d %d", &n, &m);
  for (i = 1; i <= n; i++) ans[i] = -1;
  for (i = 1; i <= n - m + 1; i++) scanf("%s", p[i]);
  tr = n - 1;
  for (i = n - m + 1; i >= 1; i--) {
    k = i + m - 1;
    if (strcmp(p[i], "NO") == 0) {
      if (ans[k] == -1) ans[k] = cnt++;
      ans[i] = ans[k];
    }
  }
  for (i = 1; i <= n; i++)
    if (ans[i] == -1) ans[i] = cnt++;
  for (i = 1; i <= n; i++) printf("%s ", na[ans[i]]);
  printf("\n");
  return 0;
}
