#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n, k;
  cin >> n >> k;
  long long arr[n + 1];
  string brr[n - k + 2];
  for (long long i = 1; i <= n - k + 1; i++) {
    cin >> brr[i];
  }
  long long counter = 1;
  if (brr[1] == "YES") {
    for (long long i = 1; i <= k; i++) {
      arr[i] = counter++;
    }
  } else {
    arr[1] = 1;
    for (long long i = 2; i <= k; i++) {
      arr[i] = counter++;
    }
  }
  long long index = k;
  for (long long i = 2; i <= n - k + 1; i++) {
    index++;
    if (brr[i] == "YES") {
      arr[index] = counter++;
    } else {
      arr[index] = arr[index - k + 1];
    }
  }
  for (long long i = 1; i <= n; i++) {
    if (arr[i] <= 26) {
      cout << char(arr[i] - 1 + 'A');
    } else {
      cout << 'A' << char(arr[i] - 26 + 'a');
    }
    cout << " ";
  }
}
