#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, i;
  cin >> n >> k;
  string s;
  cin >> s;
  i = 0;
  int c = 0;
  while (i < n) {
    if (s[i] == '.') {
      c = 0;
      i++;
    }
    if (s[i] == '#') {
      c++;
      i++;
    }
    if (c >= k) {
      cout << "NO";
      return 0;
    }
  }
  cout << "YES";
  return 0;
}
