#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  char a[n];
  cin >> a;
  int pos = 0;
  bool flag = true;
  while (pos != n - 1) {
    bool f = true;
    for (int i = k; i >= 1; i--) {
      if (pos + i < n && a[pos + i] != '#') {
        f = false;
        pos = pos + i;
        break;
      }
    }
    if (f) {
      flag = false;
      break;
    }
  }
  if (flag)
    cout << "YES";
  else
    cout << "NO";
}
