#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1.0);
const long long INFLL = 0x3f3f3f3f3f3f3f3fll;
const int maxn = 2e5 + 5;
const int mod = 1e9 + 7;
int n, k;
char ans[55][3];
int main() {
  cin >> n >> k;
  char ch1 = 'A', ch2 = 'a';
  for (int i = 0; i < n - k + 1; i++) {
    string s;
    cin >> s;
    if (i == 0) {
      if (s == "YES") {
        for (int j = i; j < i + k; j++) {
          ans[j][0] = ch1;
          ans[j][1] = ch2++;
          if (ch2 > 'z') ch1 = 'B', ch2 = 'a';
        }
      } else {
        ans[i][0] = ans[i + k - 1][0] = ch1;
        ans[i][1] = ans[i + k - 1][1] = ch2++;
        for (int j = i + 1; j < i + k - 1; j++) {
          ans[j][0] = ch1;
          ans[j][1] = ch2++;
          if (ch2 > 'z') ch1 = 'B', ch2 = 'a';
        }
      }
    } else {
      if (s == "YES") {
        ans[i + k - 1][0] = ch1;
        ans[i + k - 1][1] = ch2++;
      } else {
        ans[i + k - 1][0] = ans[i][0];
        ans[i + k - 1][1] = ans[i][1];
      }
      if (ch2 > 'z') ch1 = 'B', ch2 = 'a';
    }
  }
  for (int i = 0; i < n; i++) {
    cout << ans[i][0] << ans[i][1] << " ";
  }
  cout << endl;
  return 0;
}
