#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  vector<char> v1;
  int n, k;
  cin >> n >> k;
  for (int i = 0; i < n; i++) {
    char c;
    cin >> c;
    v1.push_back(c);
  }
  int m = 0, t = 0, z = 1;
  for (int i = 0; i < n - 1; i++) {
    if (v1[i + 1] == '#' && v1[i] == '#') {
      m = m + 1;
    } else
      m = 0;
    if (m > t) {
      t = m;
    }
    if (v1[i + 1] != '#') z = z + 1;
  }
  if (z == n) {
    cout << "YES";
  } else {
    if (t + 1 < k) {
      cout << "YES";
    } else
      cout << "NO";
  }
}
