#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 5;
int n, k, ji;
string s;
int main() {
  cin >> n >> k >> s;
  if (s[0] == '#' || s[n - 1] == '#') {
    cout << "NO\n";
    return 0;
  }
  for (int i = 0; i < n; i++) {
    if (s[i] == '#') {
      ji++;
      if (ji >= k) {
        cout << "NO\n";
        return 0;
      }
    } else
      ji = 0;
  }
  cout << "YES\n";
  return 0;
}
