#include <bits/stdc++.h>
using namespace std;
const int mx = 1000000007;
template <class T>
T bigmod(T b, T p, T m) {
  if (p == 0) return 1;
  T res = bigmod(b, p / 2, m);
  res = (res * res) % m;
  if (p % 2 == 1) res = (res * b) % m;
  return res;
}
template <class T>
T gcd(T x, T y) {
  if (y == 0) return x;
  return gcd(y, x % y);
}
int main() {
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  long long i, l = s.size(), f = 0;
  for (i = 1; i < l; i++) {
    if (s[i] == '.') {
      if ((i - f) > k)
        break;
      else
        f = i;
    }
  }
  if (f == l - 1)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
