#include <bits/stdc++.h>
using namespace std;
vector<string> arr, ans;
int main() {
  cin.sync_with_stdio(0);
  cin.tie(0);
  int n, k, i, len, ind;
  cin >> n >> k;
  string s;
  char c;
  for (i = 0; i < 26; i++) {
    s = "";
    c = (char)(i + 65);
    s = s + c;
    arr.push_back(s);
  }
  for (i = 0; i < 26; i++) {
    s = arr[i];
    c = (char)(i + 97);
    s = s + c;
    arr.push_back(s);
  }
  for (i = 0; i < k - 1; i++) {
    ans.push_back(arr[i]);
  }
  len = k - 1;
  ind = 0;
  for (i = 0; i < (n - k + 1); i++) {
    cin >> s;
    if (s == "YES") {
      ans.push_back(arr[len]);
      len++;
    } else {
      ans.push_back(ans[ind]);
    }
    ind++;
  }
  for (i = 0; i < ans.size(); i++) cout << ans[i] << " ";
  return 0;
}
