#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int x, y, aa = 0;
  cin >> x >> y;
  char arr[x + 2];
  for (int i = 0; i < x; i++) {
    cin >> arr[i];
  }
  int j = 0, jj = 1;
  for (int i = 0; i < x; i++) {
    if (arr[i] == '.') {
      if (i - j > y) {
        jj = 0;
        break;
      }
      j = i;
    }
  }
  if (jj == 1)
    cout << "YES\n";
  else
    cout << "NO\n";
  return 0;
}
