#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  vector<string> names;
  for (int i = 'A'; i <= 'Z'; ++i) {
    for (int j = 'a'; j <= 'z'; ++j) {
      string s = "";
      s.push_back(i);
      s.push_back(j);
      names.push_back(s);
    }
  }
  int n, k;
  cin >> n >> k;
  vector<long long> V(n);
  for (int i = 0; i < n; ++i) {
    string s;
    cin >> s;
    if (s == "NO") V[i] = 1;
  }
  vector<string> cur(n);
  for (int i = 0; i < cur.size(); ++i) {
    cur[i] = names[i];
  }
  for (int i = 0; i < n - k + 1; ++i) {
    if (V[i]) cur[i + k - 1] = cur[i];
  }
  for (int i = 0; i < n; ++i) {
    if (i != 0) cout << " ";
    cout << cur[i];
  }
  cout << "\n";
  return 0;
}
