#include <bits/stdc++.h>
using namespace std;
mt19937 gen(time(NULL));
const double eps = 1e-9;
const int inf = 1e9;
const int mod = 1e9 + 7;
int n, m;
int w[320];
string s;
string result[320];
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> m;
  for (int i = 0; i < n - m + 1; i++) {
    cin >> s;
    if (s == "YES")
      w[i] = 1;
    else
      w[i] = 0;
  }
  vector<string> magic1;
  vector<string> magic2;
  string curr = "a";
  for (int i = 0; i < 10; i++) {
    string curr = "a";
    curr[0] = (char)(i + 'A');
    for (int j = 0; j < 10; j++) magic1.push_back(curr + char(j + 'a'));
  }
  int j = 0;
  for (int i = 0; i < 10; i++) {
    string curr = "a";
    curr[0] = (char)(i + 'A' + 10);
    for (int j = 0; j < 10; j++) magic2.push_back(curr + char(j + 'a' + 10));
  }
  for (int i = 0; i < n - m + 1; i++) {
    if (!w[i] && result[i] == "")
      result[i] = magic1[j], result[i + m - 1] = magic1[j++];
    else if (!w[i]) {
      result[i + m - 1] = result[i];
    }
  }
  j = 0;
  for (int i = 0; i < n; i++) {
    if (result[i] == "") result[i] = magic2[j++];
  }
  for (int i = 0; i < n; i++) cout << result[i] << " ";
}
