#include <bits/stdc++.h>
using namespace std;
int main() {
  long int n, k;
  string s;
  cin >> n >> k;
  cin >> s;
  long int temp, ans;
  temp = ans = 0;
  for (long int i = 1; i < n; i++) {
    if (s[i] == '#') temp++;
    if (s[i] == '.' && s[i - 1] == '#') {
      ans = max(ans, temp);
      temp = 0;
    }
  }
  if (k > ans)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
