#include <bits/stdc++.h>
const long long int mod = 100000000000000000;
const long long int AM = 2e5 + 5;
const long long int llm = 1e18 + 7;
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long int n, k;
  cin >> n >> k;
  char ans[n + 1][3];
  char c1 = 'A', c2 = 'a';
  for (__typeof(0) i = 0; i < n; ++i) {
    ans[i][0] = c1;
    ans[i][1] = c2;
    ans[i][2] = '\0';
    if (c2 == 'z') {
      c1++;
      c2 = 'a';
    } else
      c2++;
  }
  for (__typeof(0) i = 0; i < n - k + 1; ++i) {
    string s;
    cin >> s;
    if (s == "NO") {
      ans[i + k - 1][0] = ans[i][0];
      ans[i + k - 1][1] = ans[i][1];
    }
  }
  for (__typeof(0) i = 0; i < n; ++i) cout << ans[i] << " ";
}
