#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long int n = 0, k = 0, i, c = 0, flag = 0;
  cin >> n >> k;
  string s;
  cin >> s;
  long long int f = n;
  for (i = 0; i < f; i++) {
    if (s[i] == '#')
      c++;
    else if (s[i] == '.' && c < k)
      c = 0;
    else {
      flag = 1;
      break;
    }
  }
  if (flag == 1)
    cout << "NO";
  else
    cout << "YES";
  cout << "\n";
  return 0;
}
