#include <bits/stdc++.h>
using namespace std;
int inf_int = 1e9;
long long inf_ll = 1e16;
const double pi = 3.1415926535898;
bool debug = 0;
const int MAXN = 2e5 + 100;
int mod = 1e9 + 7;
string z = "abcdef";
void get_next() { next_permutation(z.begin(), z.end()); }
string t[60];
void solve() {
  int n;
  cin >> n;
  int k;
  cin >> k;
  bool start = true;
  vector<string> ans;
  for (int i = 1; i <= n - k + 1; ++i) {
    cin >> t[i];
  }
  int cnt = 0;
  for (int i = 1; i <= n - k + 1; ++i) {
    if (t[i] == "NO")
      cnt++;
    else
      break;
  }
  ans.push_back(z);
  for (int i = 1; i <= cnt; ++i) {
    ans.push_back(z);
  }
  while (ans.size() < cnt + k - 1) {
    get_next();
    ans.push_back(z);
  }
  for (int i = cnt + 1; i <= n - k + 1; ++i) {
    if (t[i] == "NO") {
      ans.push_back(ans[ans.size() - k + 1]);
    } else {
      get_next();
      ans.push_back(z);
    }
  }
  for (auto x : ans) {
    x[0] = x[0] - 'a' + 'A';
    cout << x << " ";
  }
}
int main() {
  if (!debug) {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
  }
  int t = 1;
  while (t--) solve();
  return 0;
}
