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