#include <bits/stdc++.h>
using namespace std;
int n, k;
string cur = "a";
string mas[100];
string res[100];
int used[100];
void next() {
  if (cur[cur.size() - 1] == 'z')
    cur += "a";
  else
    cur[cur.size() - 1] += 1;
}
void mset(int l, int r) {
  for (int o = l; o <= r; o++)
    if (!used[o]) {
      used[o] = 1;
      res[o] = cur;
      next();
    }
}
int main() {
  res[0] = "a";
  cin >> n >> k;
  for (int i = 1; i <= n - k + 1; i++) cin >> mas[i];
  for (int i = 1; i <= n - k + 1; i++) {
    if (mas[i] == "YES") {
      mset(i, i + k - 1);
    } else {
      if (used[i]) {
        res[i + k - 1] = res[i];
        used[i + k - 1] = 1;
      }
    }
  }
  for (int i = n; i >= 1; i--)
    if (!used[i] && used[i + 1]) {
      used[i] = 1;
      res[i] = res[i + 1];
    }
  for (int i = 1; i <= n; i++)
    if (!used[i]) {
      used[i] = 1;
      res[i] = res[i - 1];
    }
  for (int i = 1; i <= n; i++) {
    res[i][0] -= 32;
    cout << res[i] << " ";
  }
}
