#include <bits/stdc++.h>
using namespace std;
const int maxn = 55;
char ss[maxn][3];
int main() {
  int n, k;
  while (~scanf("%d%d", &n, &k)) {
    for (int i = 1; i <= n; i++) {
      ss[i][0] = 'A' + i / 10;
      ss[i][1] = 'a' + i % 10;
      ss[i][2] = '\0';
    }
    char mid[10];
    for (int i = 1; i <= n - k + 1; i++) {
      scanf("%s", mid);
      if (!strcmp(mid, "NO")) {
        ss[i + k - 1][0] = ss[i][0];
        ss[i + k - 1][1] = ss[i][1];
      }
    }
    for (int i = 1; i <= n; i++) printf("%s ", ss[i]);
    printf("\n");
  }
  return 0;
}
