#include <bits/stdc++.h>
using namespace std;
const long long int hell = (long long int)(1e18 + 100LL);
int main() {
  long long int t, i, j, k, m, n, x, y;
  t = 1;
  while (t--) {
    long long int flag = 0;
    cin >> n >> k;
    x = n;
    n = n - k + 1;
    vector<string> ans;
    for (i = 0; i < 26; i++) {
      string s = "A";
      char c = char('a' + i);
      s += c;
      if (ans.size() < x) {
        ans.push_back(s);
      }
    }
    for (i = 0; i < 26; i++) {
      string s = "B";
      char c = char('a' + i);
      s += c;
      if (ans.size() < x) {
        ans.push_back(s);
      }
    }
    for (i = 0; i < n; i++) {
      string s;
      cin >> s;
      if (s[0] == 'N') {
        ans[i + k - 1] = ans[i];
      }
    }
    for (auto it : ans) cout << it << " ";
  }
  return 0;
}
