#include <bits/stdc++.h>
using namespace std;
const int MAX = 55;
string s[MAX], ans[MAX];
int n, k, a[MAX];
void preCal() {
  string t = "abcdefghijklmnopqrstuvwxyz";
  for (int i = 1; i <= 26; ++i) {
    s[i] = "A" + t.substr(i - 1, 1);
    s[i + 26] = "B" + t.substr(i - 1, 1);
  }
}
int main() {
  int anchor = 0;
  string temp;
  preCal();
  cin >> n >> k;
  for (int i = 1; i <= n - k + 1; ++i) {
    cin >> temp;
    if (temp == "YES")
      a[i] = 1;
    else
      a[i] = 0;
  }
  for (int i = 1; i <= n - k + 1; ++i) {
    if (a[i] == 1) {
      anchor = i;
      for (int j = i; j <= i + k - 1; ++j) {
        ans[j] = s[j];
      }
      break;
    }
  }
  if (anchor == 0) {
    for (int i = 1; i <= n; ++i) {
      cout << "A ";
    }
    return 0;
  }
  for (int i = anchor - 1; i >= 1; --i) {
    ans[i] = ans[i + k - 1];
  }
  for (int i = anchor + 1; i <= n - k + 1; ++i) {
    if (a[i] == 0) {
      ans[i + k - 1] = ans[i];
    } else {
      ans[i + k - 1] = s[i + k - 1];
    }
  }
  for (int i = 1; i <= n; ++i) {
    cout << ans[i] << " ";
  }
  return 0;
}
