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