#include <bits/stdc++.h>
using namespace std;
int b = 1;
string next();
int main() {
  int n, k;
  cin >> n >> k;
  string A[n];
  for (int i = 0; i < k; i++) A[i] = next();
  int x = n - k + 1;
  int i = k - 1;
  while (x--) {
    string S;
    cin >> S;
    if (S == "NO") {
      A[i] = A[i - k + 1];
    } else
      A[i] = next();
    i++;
  }
  for (int i = 0; i < n; i++) cout << A[i] << " ";
  cout << endl;
  return (0 - 0);
}
string name(string S) {
  S[0] = S[0] - 'a' + 'A';
  return S;
}
string next() {
  int x = b;
  string S = "";
  while (x) {
    S.push_back('a' + x % 26);
    x /= 26;
  }
  b++;
  return name(S);
}
