#include <bits/stdc++.h>
using namespace std;
const int MAX = 3 * (int)1e5 + 1;
bool a[MAX];
int main() {
  int n, k;
  char tmp;
  cin >> n >> k;
  for (int i = 0; i < n; i++) {
    cin >> tmp;
    a[i] = (tmp == '.');
  }
  for (int i = 0; i < n;) {
    if (a[i])
      i++;
    else {
      for (int j = 1; j < k; j++) {
        if (a[i + j]) {
          i += j;
          goto end;
        }
      }
      cout << "NO" << endl;
      return 0;
    }
  end : {}
  }
  cout << "YES" << endl;
  return 0;
}
