#include <bits/stdc++.h>
using namespace std;
void gen(vector<string> &a, int n) {
  for (int i = 0; i < n; i++) {
    if (i >= 26) {
      char x = (i % 26) + 'a';
      a[i] = string(2, x);
    } else {
      a[i] = string(1, i + 'a');
    }
  }
  for (int i = 0; i < n; i++) {
    a[i][0] = toupper(a[i][0]);
  }
}
int main() {
  int n, k;
  cin >> n >> k;
  vector<string> names(n);
  gen(names, n);
  vector<string> command(n);
  for (int i = 0; i < n - k + 1; i++) {
    cin >> command[i];
  }
  for (int i = 0; i < n; i++) {
    if (command[i] == "NO") {
      names[i + k - 1] = names[i];
    }
  }
  for (auto x : names) {
    cout << x << ' ';
  }
  return 0;
}
