#include <bits/stdc++.h>
using namespace std;
using ull = unsigned long long;
using ll = long long;
using ld = long double;
using D = double;
using ii = pair<int, int>;
using vi = vector<int>;
using vii = vector<ii>;
template <typename T>
T sqr(T a) {
  return a * a;
}
template <typename T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <typename T>
T sgn(T a) {
  return a > 0 ? 1 : (a < 0 ? -1 : 0);
}
template <typename T>
T abs(T a) {
  return a > 0 ? a : -a;
}
const ld pi = acos((ld)-1);
const int N = 55;
int n;
int k;
string b[N];
string a[N];
string ans[N];
int main() {
  cin >> n >> k;
  for (int i = 0; i < n - k + 1; i++) cin >> a[i];
  for (int i = 0; i < 26; i++) b[i] = (char)('A' + i);
  for (int i = 26; i < 52; i++) {
    b[i] = (char)('A' + i - 26);
    b[i] += (char)('a' + i - 26);
  }
  int z = 0;
  if (a[0][0] != 'N') {
    z = k;
    for (int i = 0; i < z; i++) {
      ans[i] = b[i];
    }
  } else {
    z = k - 1;
    for (int i = 0; i < z; i++) ans[i] = b[i];
    ans[z] = b[0];
  }
  for (int i = 1; i < n - k + 1; i++) {
    if (a[i][0] != 'N') {
      ans[k + i - 1] = b[z], z++;
    } else {
      ans[k + i - 1] = ans[i];
    }
  }
  for (int i = 0; i < n; i++) cout << ans[i] << " ";
  return 0;
}
