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