#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  string second;
  cin >> second;
  int pos1 = 0, pos2 = 0;
  for (int i = pos2; i < second.size(); i++) {
    if (second[i] == '.') {
      pos1 = i;
      for (int j = i + 1; j < second.size(); j++) {
        if (second[j] == '.') {
          pos2 = j;
          int x = count(second.begin() + pos1, second.begin() + pos2, '#');
          if (x > k - 1) {
            cout << "NO";
            return 0;
          }
          break;
        }
      }
    }
  }
  cout << "YES";
}
