#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<string> names;
  for (int i = 0; i < 26; ++i) {
    for (int j = 0; j < 26; ++j) {
      if (i == j) {
        continue;
      }
      char fr = 'A' + i;
      char sec = 'a' + j;
      string s = "aa";
      s[0] = fr;
      s[1] = sec;
      names.push_back(s);
    }
  }
  int ni = 0;
  int n, k;
  cin >> n >> k;
  string note[n];
  int nos = 0;
  for (int i = 0; i < n - k + 1; ++i) {
    cin >> note[i];
    if (note[i] == "NO") {
      nos++;
    }
  }
  if (nos == n - k + 1) {
    for (int i = 0; i < n; ++i) {
      cout << "A ";
    }
    cout << endl;
    return 0;
  }
  string ans[n];
  int r = -1;
  int i;
  for (i = 0; i < n - k + 1; ++i) {
    if (note[i] == "YES") {
      r = i + k - 1;
    }
    if (i <= r) {
      ans[i] = names[ni++];
    }
  }
  while (i <= r) {
    ans[i++] = names[ni++];
  }
  int lasty;
  for (int i = n - k; i >= 0; --i) {
    if (note[i] == "YES") {
      lasty = i;
      break;
    }
  }
  ++lasty;
  for (int i = lasty; i < n; ++i) {
    if (i + k - 1 < n) {
      ans[i + k - 1] = ans[i];
    }
  }
  for (int i = n - 1; i >= 0; --i) {
    if (i - k + 1 >= 0) {
      if (note[i - k + 1] == "NO") {
        ans[i - k + 1] = ans[i];
      }
    }
  }
  for (int i = 0; i < n; ++i) {
    cout << ans[i] << " ";
  }
  cout << endl;
  return 0;
}
