#include <bits/stdc++.h>
using namespace std;
int main() {
  int m, n, x;
  char xxx;
  string s[50], soldier[50];
  cin >> m >> n;
  x = m - n + 1;
  for (int i = 0; i < 25; i++) {
    soldier[i] = "Aa";
    soldier[i][1] += i;
  }
  for (int i = 25; i < 50; i++) {
    soldier[i] = "Ba";
    soldier[i][1] += i - 25;
  }
  for (int i = 0; i < x; i++) {
    cin >> s[i];
  }
  for (int i = 0; i < x; i++) {
    if (s[i][0] == 'N') {
      soldier[i + n - 1] = soldier[i];
    }
  }
  for (int i = 0; i < m - 1; i++) {
    cout << soldier[i] << " ";
  }
  cout << soldier[m - 1];
}
