#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  string s;
  cin >> n >> k >> s;
  bool can_reach = s[n - 1] != '#';
  for (int i = 0; i < n;) {
    if (s[i] == '#') {
      int jump = 0;
      while (i < n) {
        if (s[i] == '#')
          jump++;
        else
          break;
        i++;
      }
      if (jump > k - 1) can_reach = false;
    } else
      i++;
  }
  if (can_reach)
    cout << "YES\n";
  else
    cout << "NO\n";
  return 0;
}
