#include <bits/stdc++.h>
using namespace std;
const double sn = 1e-6;
int n, k;
char arr[55][10];
string s[55];
string res[55];
int main() {
  scanf("%d%d", &n, &k);
  for (int i = 0; i < n - k + 1; i++) {
    scanf("%s", arr[i]);
    string st(arr[i]);
    s[i] = st;
  }
  string val = "Aa";
  for (int i = 0; i < n - k + 1; i++) {
    if (s[i] == "NO") {
      if (res[i] != "") {
        res[i + k - 1] = res[i];
        continue;
      }
      res[i] = val;
      res[i + k - 1] = val;
      val[1] = val[1] + 1;
      if (val[1] > 'z') {
        val[0] = val[0] + 1;
        val[1] = 'a';
      }
    }
  }
  for (int i = 0; i < n; i++) {
    if (res[i] == "") {
      res[i] = val;
      val[1] = val[1] + 1;
      if (val[1] > 'z') {
        val[0] = val[0] + 1;
        val[1] = 'a';
      }
    }
  }
  for (int i = 0; i < n; i++) {
    printf("%s", res[i].c_str());
    if (i != n - 1) printf(" ");
  }
  printf("\n");
  return 0;
}
