#include <bits/stdc++.h>
using namespace std;
string name(long long a) {
  string res = "Aa";
  res[0] += a / 25;
  res[1] += a % 25;
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, m;
  cin >> n >> m;
  vector<bool> a(n, true);
  vector<long long> c(n, -1);
  vector<string> b(n);
  string qq;
  long long y = -1;
  for (long long i = 0; i < n - m + 1; i++) {
    cin >> qq;
    a[i] = (qq == "YES");
    if (a[i]) {
      if (i != 0 && !a[i - 1]) c[i - 1] = i - y;
    } else {
      if (i == 0 || a[i - 1]) y = i;
    }
  }
  for (long long i = 0; i < n; i++) {
    b[i] = name(i);
  }
  for (long long i = 0; i < n - m + 1; i++) {
    if (!a[i]) b[i + m - 1] = b[i];
  }
  cout << b[0];
  for (long long i = 1; i < n; i++) cout << " " << b[i];
}
