#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  string s[56], p[50], res[53];
  char na = 'A';
  for (int i = 1; i <= 26; i++) {
    s[i] = na++;
  }
  na = 'A';
  char u = 'a';
  for (int i = 27; i <= 50; i++) {
    s[i] = na;
    p[i] = u++;
    s[i] += p[i];
  }
  for (int i = 1; i <= (n - m) + 1; i++) {
    string ni;
    cin >> ni;
    res[i] = ni;
  }
  for (int i = 1; i <= n - m + 1; i++) {
    if (res[i] == "NO") {
      s[i + m - 1] = s[i];
    }
  }
  for (int i = 1; i <= n; i++) {
    cout << s[i] << " ";
  }
  return 0;
}
