#include <bits/stdc++.h>
using namespace std;
string str[60], ans[60];
void init() {
  ans[1] = "A";
  ans[2] = "B";
  ans[3] = "C";
  ans[4] = "D";
  ans[5] = "E";
  ans[6] = "F";
  ans[7] = "G";
  ans[8] = "H";
  ans[9] = "I";
  ans[10] = "Aa";
  ans[11] = "Ab";
  ans[12] = "Ba";
  ans[13] = "Ca";
  ans[14] = "Da";
  ans[15] = "Ea";
  ans[16] = "Fa";
  ans[17] = "Ga";
  ans[18] = "Ha";
  ans[19] = "Ia";
  ans[20] = "Aaa";
  ans[21] = "Aba";
  ans[22] = "Baa";
  ans[23] = "Caa";
  ans[24] = "Daa";
  ans[25] = "Eaa";
  ans[26] = "Faa";
  ans[27] = "Gaa";
  ans[28] = "Haa";
  ans[29] = "Iaa";
  ans[30] = "Abbb";
  ans[31] = "Aaaa";
  ans[32] = "Baaa";
  ans[33] = "Caaa";
  ans[34] = "Daaa";
  ans[35] = "Eaaa";
  ans[36] = "Faaa";
  ans[37] = "Gaaa";
  ans[38] = "Haaa";
  ans[39] = "Iaaa";
  ans[40] = "Accc";
  ans[41] = "Ac";
  ans[42] = "Bc";
  ans[43] = "Cc";
  ans[44] = "Dc";
  ans[45] = "Ec";
  ans[46] = "Fc";
  ans[47] = "Gc";
  ans[48] = "Hc";
  ans[49] = "Ic";
  ans[50] = "Acccccc";
  ans[51] = "Afffff";
}
int main() {
  int n, k;
  while (cin >> n >> k) {
    init();
    int m = n - k + 1;
    for (int i = 1; i <= m; i++) cin >> str[i];
    for (int i = 1; i <= m; i++) {
      if (str[i] == "NO") {
        ans[i + k - 1] = ans[i];
      }
    }
    for (int i = 1; i < n; i++) cout << ans[i] << " ";
    cout << ans[n] << endl;
  }
  return 0;
}
