#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, cc = 0, max = 0;
  string r;
  cin >> n >> k;
  cin >> r;
  for (int i = 0; i < n; i++) {
    if (r[i] == '#') {
      while (r[i] != '.') {
        i++;
        cc++;
      }
      if (cc > max) max = cc;
      cc = 0;
    }
  }
  if (k <= max)
    cout << "NO";
  else
    cout << "YES";
}
