#include <bits/stdc++.h>
using namespace std;
using namespace std;
const int MAXN = 100;
const int LG = 20;
const int INF = 1e7 + 9;
class DSU {
 public:
  int x, y, z;

 private:
  vector<int> v[200001];
};
int n, k;
string s[51], ans[51];
int main() {
  cin >> n >> k;
  for (int i = 1; i <= n - k + 1; ++i) cin >> s[i];
  string tarieils_audga[10001];
  for (int i = 0; i < 26; ++i) {
    char ch = (char)'A' + i;
    for (int j = 0; j < 26; ++j) {
      char ch1 = (char)'a' + j;
      tarieils_audga[i * 26 + j] += ch;
      tarieils_audga[i * 26 + j] += ch1;
    }
  }
  ans[1] = tarieils_audga[1];
  int pos = 1, nestan_mieci = 1;
  for (int i = 1; i <= n - k + 1; ++i) {
    if (s[i] == "YES") {
      while (nestan_mieci < i + k - 1)
        ans[++nestan_mieci] = tarieils_audga[++pos];
    } else {
      ans[++nestan_mieci] = ans[i];
    }
  }
  while (nestan_mieci < n) ans[++nestan_mieci] = ans[++pos];
  for (int i = 1; i <= n; ++i) cout << ans[i] << " ";
  return 0;
}
