#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
void solve() {
  int n, k;
  cin >> n >> k;
  int m = n - k + 1;
  vector<string> a(100), in(m);
  for (int i = 0; i < 26; i++) {
    a[i] = "A";
    a[i] += char('a' + i);
  }
  for (int i = 26; i < 52; i++) {
    a[i] = "B";
    a[i] += char('a' + i - 26);
  }
  for (int i = 0; i < m; i++) {
    cin >> in[i];
  }
  for (int i = 0; i < m; i++) {
    if (in[i] == "NO") {
      a[i + k - 1] = a[i];
    }
  }
  for (int i = 0; i < n; i++) {
    cout << a[i] << " ";
  }
}
int main() {
  srand(time(NULL));
  int t;
  solve();
  return 0;
}
