#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  int n, k;
  cin >> n >> k;
  string sectors;
  cin >> sectors;
  if (sectors[0] == '#' or sectors[n - 1] == '#') {
    cout << "NO" << '\n';
    return 0;
  }
  int count = 0;
  for (int i = 1; i < n - 1; ++i) {
    if (sectors[i] == '#')
      ++count;
    else
      count = 0;
    if (count >= k) {
      cout << "NO" << '\n';
      return 0;
    }
  }
  cout << "YES" << '\n';
  return 0;
}
