#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  string now = "Aa";
  vector<string> ans;
  for (int i = 0; i < k - 1; i++) {
    ans.push_back(now);
    if (now.back() == 'z') {
      now += "a";
    } else {
      now.back()++;
    }
  }
  for (int i = 0; i < n - k + 1; i++) {
    string s;
    cin >> s;
    if (s == "NO") {
      ans.push_back(ans[i]);
    } else {
      ans.push_back(now);
      if (now.back() == 'z') {
        now += "a";
      } else {
        now.back()++;
      }
    }
  }
  for (int i = 0; i < n; i++) {
    cout << ans[i] << " ";
  }
}
