#include <bits/stdc++.h>
using ll = long long;
using ull = unsigned long long;
using std::cin;
using std::cout;
int main() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(NULL);
  int n, k;
  cin >> n >> k;
  std::vector<bool> stat;
  for (int i = 0; i < n - k + 1; ++i) {
    std::string str;
    cin >> str;
    if (str == "NO")
      stat.push_back(false);
    else
      stat.push_back(true);
  }
  std::vector<std::string> names;
  char s[3] = "00";
  for (char i = 'A'; i <= 'Z'; ++i) {
    for (char j = 'a'; j <= 'z'; ++j) {
      s[0] = i;
      s[1] = j;
      names.push_back(std::string(s));
    }
  }
  std::deque<std::string> Q;
  int index = 0;
  for (int i = 0; i < k - 1; ++i) {
    cout << names[index] << " ";
    Q.push_back(names[index++]);
  }
  for (int i = 0; i < stat.size(); ++i) {
    if (stat[i]) {
      Q.pop_front();
      cout << names[index] << " ";
      Q.push_back(names[index++]);
    } else {
      cout << Q.front() << " ";
      Q.push_back(Q.front());
      Q.pop_front();
    }
  }
  return 0;
}
