#include <bits/stdc++.h>
using namespace std;
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T>
inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int dx[] = {-1, 1, 0, 0};
const int dy[] = {0, 0, 1, -1};
int n, k;
string s;
vector<int> inv;
int main() {
  cin >> n >> k >> s;
  int crt = 0;
  for (int i = (0); i < (n); ++i) {
    if (s[i] == '.') {
      if (crt) inv.push_back(crt);
      crt = 0;
    } else {
      crt++;
    }
  }
  if (crt) inv.push_back(crt);
  for (int i = (0); i < (inv.size()); ++i) {
    if (inv[i] >= k) {
      cout << "NO" << endl;
      return 0;
    }
  }
  cout << "YES" << endl;
  return 0;
}
