#include <bits/stdc++.h>
using namespace std;
int N, K;
int a[100];
char s[100][4];
int b[100];
int main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> N >> K;
  int first = -1;
  for (int i = 0; i < N - K + 1; i++) {
    string x;
    cin >> x;
    a[i] = x.compare("YES") == 0 ? 1 : 0;
    if (first < 0 && a[i] == 1) first = i;
  }
  for (int i = 0; i < 26; i++) {
    s[i][0] = 'A' + i;
  }
  for (int i = 26; i < 52; i++) {
    s[i][0] = 'A' + i - 26;
    s[i][1] = 'a';
  }
  if (first < 0) {
    for (int i = 0; i < N; i++) {
      cout << 'A';
      if (i == N - 1)
        cout << endl;
      else
        cout << ' ';
    }
    return 0;
  }
  for (int i = 0; i < first; i++) {
    b[i] = 0;
  }
  for (int i = first; i < first + K; i++) {
    b[i] = i - first;
  }
  for (int i = first + 1; i < N - K + 1; i++) {
    if (a[i] == 0)
      b[i + K - 1] = b[i];
    else
      b[i + K - 1] = i + K - 1;
  }
  for (int i = 0; i < N; i++) {
    cout << s[b[i]];
    if (i == N - 1)
      cout << endl;
    else
      cout << ' ';
  }
  return 0;
}
