#include <bits/stdc++.h>
using namespace std;
void func() {
  long long int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  vector<long long int> v;
  for (long long int i = 0; i < n; ++i) {
    if (s[i] == '.') v.push_back(i);
  }
  for (long long int i = 1; i < v.size(); i++) {
    if (v[i] - v[i - 1] > k) {
      cout << "NO\n";
      return;
    }
  }
  cout << "YES\n";
}
int32_t main() {
  func();
  return 0;
}
