#include <bits/stdc++.h>
using namespace std;
long long n, k, m;
vector<string> pool;
vector<string> input;
string ans[1000001];
string s;
long long cnt = 0;
bool vis[1000001];
int main() {
  char ch = 'A';
  char ch2 = 'a';
  for (long long i = 0; i < 26; i++) {
    string h;
    h.push_back(ch);
    pool.push_back(h);
    ch++;
  }
  ch = 'A';
  for (long long i = 0; i < 25; i++) {
    string h;
    h.push_back(ch);
    h.push_back(ch2);
    pool.push_back(h);
    ch++;
    ch2++;
  }
  cin >> n >> k;
  m = 0;
  while (m < n - k + 1) {
    cin >> s;
    for (long long j = m; j <= m + k - 1; j++) {
      if (vis[j] == false and j != m + k - 1) {
        ans[j] = pool[cnt++];
        vis[j] = true;
      } else if (j == m + k - 1 and s == "NO") {
        ans[j] = ans[j - k + 1];
        vis[j] = true;
      } else if (j == m + k - 1) {
        ans[j] = pool[cnt++];
        vis[j] = true;
      }
    }
    m++;
  }
  for (long long i = 0; i < n; i++) cout << ans[i] << " ";
  return 0;
}
