#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<string> v;
  for (long long int i = 0; i < 26; i++) {
    string u = "";
    char c = 'A' + i;
    for (long long int j = 0; j < 26; j++) {
      char t = 'a' + j;
      u = "";
      u += c;
      u += t;
      v.push_back(u);
    }
  }
  long long int n, m;
  cin >> n >> m;
  vector<string> vec, input(n);
  for (long long int i = 0; i < n; i++) {
    vec.push_back(v[i]);
  }
  for (long long int i = 0; i < n - m + 1; i++) {
    cin >> input[i];
    if (input[i] == "NO") {
      v[i + m - 1] = v[i];
    }
  }
  for (long long int i = 0; i < n; i++) {
    cout << v[i] << " ";
  }
  cout << endl;
}
