#include <bits/stdc++.h>
using namespace std;
struct sol {
  string st;
  int f, l;
  sol(string a, int b, int c) {
    st = a;
    f = b;
    l = c;
  }
};
int main() {
  string name[52];
  for (int i = 0; i < 26; i++) {
    name[i] = char('A' + i);
  }
  for (int i = 26; i < 52; i++) {
    name[i] = char('A' + i - 26);
    name[i] += "a";
  }
  int n, k;
  cin >> n >> k;
  int a[n + 1][n + 1];
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      a[i][j] = 1;
    }
  }
  string p, last = "";
  for (int i = 1; i <= n - k + 1; i++) {
    cin >> p;
    if (p == "NO") {
      name[k + i - 1] = name[i];
    }
  }
  for (int i = 1; i <= n; i++) {
    cout << name[i] << " ";
  }
  return 0;
}
