#include <bits/stdc++.h>
using namespace std;
long long n, k, i, j, sum, updated[100];
string s;
vector<string> store, query;
vector<string> ans(70);
int main() {
  for (i = 0; i <= 99; i++) updated[i] = -1;
  cin >> n >> k;
  for (i = 1; i <= n - k + 1; i++) {
    cin >> s;
    query.push_back(s);
  }
  j = 0;
  char ch = 'a';
  s = "A";
  for (i = 0; i <= n - 1; i++) {
    s += ch;
    ans[i] = s;
    if (ch == 'z')
      s = "B", ch = 'a';
    else
      s.pop_back(), ch++;
  }
  for (i = 0; i <= n - 1; i++) {
    string sss = ans[i];
    sss[0] = toupper(sss[0]);
    ans[i] = sss;
  }
  for (i = 0; i <= n - 1; i++)
    ;
  for (i = 0; i <= n - k; i++) {
    if (query[i] == "NO") {
      ans[i] = ans[i + k - 1];
      updated[i + k - 1] = i;
      j = i;
      while (j >= 0) ans[j] = ans[i], j = updated[j];
    }
  };
  for (i = 0; i <= n - 1; i++) printf("%s ", ans[i].c_str());
  return 0;
}
