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