#include <bits/stdc++.h>
using namespace std;
template <class T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <class T>
T lcm(T a, T b) {
  return a * b / gcd(a, b);
};
vector<string> split(string s) {
  istringstream buf(s);
  istream_iterator<string> beg(buf), end;
  vector<string> list(beg, end);
  return list;
}
bool isvowel(char c) {
  string s = "aeiou";
  if (find(s.begin(), s.end(), c) != s.end()) return true;
  return false;
}
bool cmp(pair<int, int> &a, pair<int, int> &b) {
  return a.second > b.second || (a.second == b.second && a.first > b.first);
}
void sieve(int n) {
  int prime[1000005];
  for (int i = 2; i <= n; i++) {
    prime[i] = 1;
  }
  for (int i = 2; i * i <= n; i++) {
    if (prime[i])
      for (int j = i * 2; j <= n; j += i) {
        prime[j] = false;
      }
  }
}
void solve() {
  int n, k;
  cin >> n >> k;
  vector<string> v(n - k + 1);
  vector<string> ans(n);
  for (int i = 0; i <= n - k; i++) cin >> v[i];
  for (int i = 0; i < n; i++) {
    string s;
    s.push_back('A' + i / 26);
    s.push_back('a' + i % 26);
    ans[i] = s;
  }
  for (int i = 0; i <= n - k; i++) {
    if (v[i] == "NO") {
      ans[i + k - 1] = ans[i];
    }
  }
  for (auto s : ans) cout << s << ' ';
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cout << setprecision(20);
  int t = 1;
  for (int test_case = 1; test_case <= t; test_case++) {
    solve();
  }
  return 0;
}
