#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, k, i, j;
  cin >> n >> k;
  int a[n - k + 1];
  string s;
  for (i = 0; i < n - k + 1; i++) {
    cin >> s;
    if (s[0] == 'Y')
      a[i] = 0;
    else
      a[i] = 1;
  }
  vector<string> ans;
  char a1 = 'a', b = 'a';
  string v = "";
  i = 0;
  for (i = 0; i < k; i++) {
    ans.push_back(v + a1);
    if (a1 == 'z') {
      v = b;
      b++;
      a1 = 'a';
    } else
      a1++;
  }
  if (a[0] == 1) {
    ans[k - 1] = ans[0];
    a1--;
  }
  j = 1;
  for (i = 1; i < n - k + 1; i++) {
    if (a[i] == 1)
      ans.push_back(ans[i]);
    else {
      ans.push_back(v + a1);
      if (a1 == 'z') {
        v = b;
        b++;
        a1 = 'a';
      } else
        a1++;
    }
  }
  for (i = 0; i < n; i++) ans[i][0] -= 32;
  for (i = 0; i < n; i++) cout << ans[i] << " ";
}
