#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
int lcm(int a, int b) { return (b / gcd(a, b)) * a; }
void print() {}
void pLine() { cout << endl; }
template <class T, class... arg>
void print(T x, arg... ar) {
  cout << x;
  print(ar...);
}
using ll = long long;
using ii = pair<int, int>;
using vi = vector<int>;
using vii = vector<ii>;
using vs = vector<string>;
using vb = vector<bool>;
using ld = long double;
using ull = unsigned long long;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ll n, k;
  string s[50], ans[51];
  cin >> n >> k;
  for (int i = (int)0; i < (int)n - k + 1; i++) {
    cin >> s[i];
  }
  for (int i = (int)1; i < (int)k + 1; i++) {
    ans[i] = "A";
    ans[i].push_back(char(i / 26 + int('a')));
    ans[i].push_back(char(i % 26 + int('a')));
  }
  for (int i = (int)0; i < (int)(n - k + 1) + 1; i++) {
    if (s[i] == "YES") {
      ans[i + k] = "A";
      ans[i + k] = ans[i + k] + char((i + k) / 26 + int('a'));
      ans[i + k] = ans[i + k] + char((i + k) % 26 + int('a'));
    } else
      ans[i + k] = ans[i + 1];
  }
  for (int i = (int)1; i < (int)n + 1; i++) cout << ans[i] << ' ';
  return 0;
}
