#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
const int mod = 1e9 + 7;
void D(vector<int> a) {
  for (int i : a) cout << i << " ";
  cout << endl;
}
void solve() {
  int n, k;
  cin >> n >> k;
  vector<string> a(n, "A");
  a[0] += "a";
  for (int i = 1; i < n; i++) {
    if (i < 26)
      a[i] += char(i + 'a');
    else {
      a[i] += char(i - 26 + 'a');
      a[i] += char(i - 26 + 'a');
    }
  }
  string t;
  for (int i = 0; i < n - k + 1; i++) {
    if ((cin >> t), t == "NO") a[i + k - 1] = a[i];
  }
  for (auto i : a) cout << i << " ";
  cout << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  solve();
  return 0;
}
