#include <bits/stdc++.h>
using namespace std;
template <typename T>
T sqr(T x) {
  return x * x;
}
template <typename T>
T abs(T x) {
  return x > 0 ? x : -x;
}
int cur = 0;
string get_next() {
  string ans = "";
  if (cur >= 26) {
    ans = "B";
  } else {
    ans = "A";
  }
  ans += (char)('a' + cur % 26);
  cur++;
  return ans;
}
int main() {
  int n, k;
  cin >> n >> k;
  vector<bool> used(n - k + 1);
  for (int i = 0; i < n - k + 1; i++) {
    string s;
    cin >> s;
    if (s == "NO") {
      used[i] = true;
    }
  }
  vector<string> ans(n);
  for (int i = 0; i < n; i++) {
    if (i >= k - 1 && used[i - k + 1]) {
      ans[i] = ans[i - k + 1];
    } else {
      ans[i] = get_next();
    }
  }
  for (int i = 0; i < n; i++) {
    cout << ans[i] << " ";
  }
  cout << "\n";
  return 0;
}
