#include <bits/stdc++.h>
using namespace std;
long long n, m, ans;
string a[55], ss[55], s[55];
void z() {
  for (int i = 1; i <= 26; i++) {
    a[i] = 'A' + i - 1;
  }
  for (int i = 27; i <= 52; i++) {
    a[i] = 'a' + i - 27;
    a[i] = 'A' + a[i];
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  z();
  cin >> n >> m;
  for (int i = 1; i <= n - m + 1; i++) {
    cin >> s[i];
  }
  if (s[1] == "YES") {
    for (int i = 1; i <= m; i++) {
      ss[i] = a[i];
      cout << a[i] << " ";
    }
    ans = m + 1;
  } else {
    for (int i = 1; i <= m - 1; i++) {
      ss[i] = a[i];
      cout << a[i] << " ";
    }
    ss[m] = a[1];
    cout << a[1] << " ";
    ans = m;
  }
  for (int i = 2; i <= n - m + 1; i++) {
    if (s[i] == "YES") {
      ss[i + m - 1] = a[ans];
      ans++;
      cout << ss[i + m - 1] << " ";
    } else {
      ss[i + m - 1] = ss[i];
      cout << ss[i] << " ";
    }
  }
  cout << '\n';
  return 0;
}
