#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  char road[n];
  for (int i = 0; i < n; i++) cin >> road[i];
  int pos = 0;
  while (pos < n) {
    int count = 0;
    while (pos < n) {
      if (road[pos] == '.') break;
      count++;
      pos++;
    }
    if (count >= k) {
      cout << "NO" << endl;
      return 0;
    }
    pos++;
  }
  cout << "YES" << endl;
  return 0;
}
