#include <bits/stdc++.h>
using namespace std;
map<long long int, string> lists;
void init() {
  lists[1] = "A";
  lists[2] = "B";
  lists[3] = "C";
  lists[4] = "D";
  lists[5] = "E";
  lists[6] = "F";
  lists[7] = "G";
  lists[8] = "H";
  lists[9] = "I";
  lists[10] = "J";
  lists[11] = "K";
  lists[12] = "L";
  lists[13] = "M";
  lists[14] = "N";
  lists[15] = "O";
  lists[16] = "P";
  lists[17] = "Q";
  lists[18] = "R";
  lists[19] = "S";
  lists[20] = "T";
  lists[21] = "U";
  lists[22] = "V";
  lists[23] = "W";
  lists[24] = "X";
  lists[25] = "Y";
  lists[26] = "Z";
  lists[27] = "Ab";
  lists[28] = "Ac";
  lists[29] = "Ad";
  lists[30] = "Ae";
  lists[31] = "Af";
  lists[32] = "Ag";
  lists[33] = "Ah";
  lists[34] = "Ai";
  lists[35] = "Aj";
  lists[36] = "Ak";
  lists[37] = "Al";
  lists[38] = "Am";
  lists[39] = "An";
  lists[40] = "Ao";
  lists[41] = "Ap";
  lists[42] = "Aq";
  lists[43] = "Ar";
  lists[44] = "As";
  lists[45] = "At";
  lists[46] = "Au";
  lists[47] = "Av";
  lists[48] = "Aw";
  lists[49] = "Ax";
  lists[50] = "Ay";
  lists[51] = "Az";
}
int main() {
  init();
  vector<string> ans;
  long long int n, m;
  cin >> n >> m;
  ans.push_back("a");
  for (long long int i = 1; i <= n; i++) ans.push_back(lists[i]);
  for (long long int i = 1; i <= n - m + 1; i++) {
    string ss;
    cin >> ss;
    if (ss == "NO") ans[i + m - 1] = ans[i];
  }
  for (long long int i = 1; i <= n; i++) cout << ans[i] << " ";
  cout << endl;
  return 0;
}
