#include <bits/stdc++.h>
using namespace std;
string str[55];
string ch;
string name[55];
map<string, int> used;
int main() {
  int n, m;
  scanf("%d %d", &n, &m);
  int k = n - m + 1;
  for (int i = 0; i < 26; i++) {
    name[i] = 'A' + i;
  }
  for (int i = 26; i <= 50; i++) {
    name[i] = name[i - 26] + "a";
  }
  for (int i = 0; i < m - 1; i++) {
    str[i] = name[i];
    used[str[i]]++;
  }
  for (int i = m - 1; i < k + m - 1;) {
    cin >> ch;
    if (ch == "NO") {
      str[i] = str[i - m + 1];
      used[str[i]]++;
    } else {
      for (int j = 0; j <= 50; j++) {
        if (!used[name[j]]) {
          str[i] = name[j];
          used[name[j]]++;
          break;
        }
      }
    }
    i++;
    used[str[i - m]]--;
  }
  for (int i = 0; i < n; i++) {
    cout << str[i] << " ";
  }
  cout << endl;
}
