#include <bits/stdc++.h>
using namespace std;
int main() {
  string s[105], ans[105];
  int n, k, cnt = 0;
  int i;
  int now = 1;
  scanf("%d%d", &n, &k);
  for (i = 1; i <= n - k + 1; i++) cin >> s[i];
  for (i = 0; i < n; ++i) {
    if (cnt < 26)
      ans[i] = "A";
    else
      ans[i] = "B";
    ans[i] += (char)('a' + cnt % 26);
    cnt++;
  };
  for (i = 1; i <= n - k + 1; ++i) {
    if (s[i] == "NO") ans[i + k - 2] = ans[i - 1];
  }
  for (i = 0; i < n; i++) cout << ans[i] << " ";
}
