#include <bits/stdc++.h>
using namespace std;
char name[55][10];
char sir[10];
int rez[55];
void nxt() {
  if (sir[2] == 'z') {
    sir[2] = 'a';
    sir[1]++;
  } else {
    sir[2]++;
  }
}
int main() {
  int N, K;
  cin >> N >> K;
  for (int i = 1; i <= N - K + 1; ++i) {
    cin >> sir;
    if (strcmp(sir, "NO") == 0) {
      rez[i] = -1;
    } else {
      rez[i] = 1;
    }
  }
  strcpy(sir, "Aaa");
  int in = 1;
  int sf = K;
  strcpy(name[1], "Aaa");
  nxt();
  int pos = 2;
  for (int i = 1; i <= N - K + 1; ++i) {
    if (rez[i] == -1) {
      strcpy(name[pos], name[in]);
      ++in;
      ++sf;
      ++pos;
    } else {
      while (pos <= sf) {
        strcpy(name[pos], sir);
        nxt();
        ++pos;
      }
      ++in;
      ++sf;
    }
  }
  while (pos <= N) {
    strcpy(name[pos], sir);
    nxt();
    ++pos;
  }
  for (int i = 1; i <= N; ++i) {
    cout << name[i] << ' ';
  }
  cout << '\n';
  return 0;
}
