#include <bits/stdc++.h>
using namespace std;
bool vis[150002];
int cnt[150002];
vector<int> edge[150002];
int nd, ed;
int main() {
  string str[100];
  char j = 'A', k;
  for (int i = 1; i <= 26; i++, j++) str[i] = j;
  j = 'a', k = 'A';
  for (int i = 27; i <= 52; i++, j++, k++) {
    str[i] = k;
    str[i] += j;
  }
  double L, H, W;
  int n, m;
  while (cin >> n >> m) {
    string st;
    vector<string> ans;
    int k = 1;
    for (int i = 0; i < n - m + 1; i++) {
      cin >> st;
      if (i == 0) {
        if (st == "YES") {
          for (int j = i; j < i + m; j++) {
            ans.push_back(str[k++]);
          }
        } else {
          for (int j = i; j < i + m - 1; j++) {
            ans.push_back(str[k++]);
          }
          ans.push_back(str[1]);
        }
      } else {
        if (st == "YES") {
          ans.push_back(str[k++]);
        } else {
          string ss = ans[i];
          ans.push_back(ss);
        }
      }
    }
    for (int i = 0; i < ans.size(); i++) cout << ans[i] << ' ';
    cout << endl;
  }
  return 0;
}
