#include <bits/stdc++.h>
using namespace std;
int mod = 1000000007;
int m, n, k, p1, p2, p3, p, f, a[1000], pr[1000], c[1000], x[1000];
string s[60], ans[60];
int xxx(int i, int j) {
  for (int l = i - 1; l >= 0; l--) {
    int y = 0;
    for (int ll = i; ll < (int)(j); ll++)
      if (x[ll] == x[l]) y = 1;
    if (c[l] && !y) return x[l];
  }
  for (int j = 0; j < (int)(52); j++)
    if (pr[j] < i + 1) return j;
  return 0;
}
int main() {
  for (int i = 0; i < (int)(26); i++) {
    s[i] = 'A' + i;
    s[i + 26] = s[i];
    s[i] += 'a';
    s[i + 26] += 'b';
  }
  cin >> n >> k;
  for (int i = 0; i < (int)(n - k + 1); i++) {
    string xx;
    cin >> xx;
    if (xx[0] == 'Y')
      a[i] = 1;
    else
      a[i] = 0;
  }
  for (int i = 0; i < (int)(n - k + 1); i++) {
    if (a[i] == 1) {
      for (int j = i; j < (int)(i + k); j++)
        if (!c[j]) {
          x[j] = xxx(i, j);
          pr[x[j]] = j + 1;
          c[j] = 1;
        }
    }
  }
  for (int i = 0; i < (int)(n - k + 1); i++)
    if (!a[i]) {
      for (int j = i; j < (int)(i + k); j++)
        if (c[j]) {
          p1 = x[j];
          break;
        }
      for (int j = i; j < (int)(i + k); j++)
        if (!c[j]) {
          x[j] = p1;
          if (!j) x[j] = x[j - 1];
          c[j] = 1;
          break;
        }
    }
  for (int i = 0; i < (int)(n); i++)
    if (!c[i]) x[i] = 0;
  for (int i = 0; i < (int)(n); i++) cout << s[x[i]] << " ";
  return 0;
}
