#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, i;
  cin >> n >> k;
  string arr[n];
  string dummy;
  int cap = 65, sm = 97;
  for (i = 0; i < n; i++) {
    dummy = "";
    if (sm == 123) {
      cap++;
      sm = 97;
    }
    dummy.push_back((char)cap);
    dummy.push_back((char)sm);
    sm++;
    arr[i] = dummy;
  }
  for (i = 0; i <= n - k; i++) {
    cin >> dummy;
    if (dummy == "NO") {
      arr[i + k - 1] = arr[i];
    }
  }
  for (i = 0; i < n; i++) {
    cout << arr[i] << " ";
  }
  cout << endl;
  return 0;
}
