#include <bits/stdc++.h>
using namespace std;
int n, k;
string s;
char c[150005];
vector<string> imena;
void generiraj() {
  for (char sl2 = 'a'; sl2 <= 'z'; sl2++) {
    for (char sl1 = 'A'; sl1 <= 'Z'; sl1++) {
      string tmp = "";
      tmp += sl1;
      tmp += sl2;
      imena.push_back(tmp);
    }
  }
}
void ispisi() {
  for (int i = 0; i < n; i++) {
    cout << imena[i] << " ";
  }
  cout << endl;
}
void unesi() {
  scanf("%d %d", &n, &k);
  for (int i = 0; i < n - k + 1; i++) {
    cin >> s;
    c[i] = s[0];
  }
}
int main() {
  unesi();
  generiraj();
  int br = 0;
  for (int poc = 0; poc <= n - k; poc++) {
    if (c[br] == 'N') {
      imena[poc + k - 1] = imena[poc];
    }
    br++;
  }
  ispisi();
  return 0;
}
