#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18 + 4;
const int MAXN = 5 * 1e5 + 1, MODM = 1e9 + 1;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n, k;
  cin >> n >> k;
  vector<int> res(n);
  for (int i = 0; i < n - k + 1; ++i) {
    string s;
    cin >> s;
    if (s == "YES") {
      res[i] = 1;
    } else {
      res[i] = 0;
    }
  }
  vector<string> name;
  for (char f = 'A'; f <= 'Z'; ++f) {
    for (char q = 'a'; q <= 'z'; ++q) {
      string ss;
      ss += f;
      ss += q;
      name.push_back(ss);
    }
  }
  vector<string> ans(n);
  bool good = 0;
  for (int i = 0; i < n - k + 1; ++i) {
    if (res[i] == 1) {
      good = 1;
      for (int j = 0; j < k; ++j) {
        if (ans[i + j].empty()) {
          ans[i + j] = name.back();
          name.pop_back();
        }
      }
    } else {
      string ss = ans[i];
      if (ss.empty()) {
        ss = name.back();
        name.pop_back();
        ans[i] = ss;
      }
      for (int j = 0; j < k; ++j) {
        if (ans[i + j].empty()) {
          ans[i + j] = ss;
          break;
        }
      }
    }
  }
  if (!good) {
    for (int i = 0; i < n; ++i) {
      cout << 'A' << ' ';
    }
    cout << endl;
    return 0;
  }
  for (auto s : ans) {
    cout << s << ' ';
  }
  cout << endl;
  return 0;
}
