#include <bits/stdc++.h>
using namespace std;
const int inf = int(1e9);
string str(int x) {
  string s = "";
  while (x) {
    if (s.size() == 0) {
      s += 'A' + (x % 10);
    } else {
      s += 'a' + (x % 10);
    }
    x /= 10;
  }
  return s;
}
int main() {
  int n, k;
  cin >> n >> k;
  int cnt = n - k + 1;
  vector<string> a(cnt);
  for (int i = 0; i < cnt; i++) {
    cin >> a[i];
  }
  vector<int> b(n);
  for (int i = 0; i < k - 1; i++) {
    b[i] = i;
  }
  for (int i = 0; i < cnt; i++) {
    if (a[i] == "YES") {
      b[i + k - 1] = i + k - 1;
    } else {
      b[i + k - 1] = b[i];
    }
  }
  for (int el : b) cout << str(el + 1) << " ";
}
