#include <bits/stdc++.h>
using namespace std;
int main() {
  iostream::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, k;
  cin >> n >> k;
  vector<string> ans(n);
  ans[0] = 'A';
  for (auto(i) = (1); (i) < (n); (i)++) {
    ans[i] = ans[i - 1];
    if (ans[i].back() != 'Z')
      ans[i].back()++;
    else
      ans[i].back() = 'A', ans[i].push_back('a');
  }
  for (auto(i) = (k - 1); (i) < (n); (i)++) {
    string s;
    cin >> s;
    if (s == "NO") ans[i] = ans[i - k + 1];
  }
  for (auto(i) = (0); (i) < (n); (i)++) cout << ans[i] << ' ';
  return 0;
}
