#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  int last_save = 1;
  for (int i = 0; i < n; i++) {
    char c;
    cin >> c;
    if (c == '.') {
      last_save = i + 1;
    } else {
      if (i + 1 - last_save >= k) {
        cout << "NO\n";
        return 0;
      }
    }
  }
  cout << "YES\n";
  return 0;
}
