#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  vector<string> name(n - k + 1);
  for (int i = 0; i < n - k + 1; ++i) {
    cin >> name[i];
  }
  vector<int> resh(n);
  resh[0] = 0;
  int last = 0;
  int glob = 1;
  for (int i = 0; i < n - k + 1; ++i) {
    if (name[i] == "YES") {
      for (int j = last + 1; j < i + k; ++j) {
        resh[j] = glob;
        glob++;
        last++;
      }
    }
    if (name[i] == "NO") {
      resh[last + 1] = resh[i];
      last++;
    }
  }
  char a;
  char b;
  for (int i = 0; i < n; i++) {
    if (resh[i] <= 25) {
      a = 'A' + resh[i];
      cout << a << " ";
    } else {
      a = 'A' + 25;
      b = 'a' + resh[i] % 26;
      cout << a << b << " ";
    }
  }
  return 0;
}
