#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  string str;
  cin >> str;
  vector<int> arr;
  for (int i = 0; i < str.size(); i++) {
    if (str[i] == '.') arr.push_back(i + 1);
  }
  for (int i = 0; i + 1 < arr.size(); i++) {
    if (arr[i] + k < arr[i + 1]) {
      cout << "NO" << endl;
      return 0;
    }
  }
  cout << "YES" << endl;
  return 0;
}
