#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  int a[300010] = {0};
  a[0] = 0;
  int c = 0;
  for (int i = 1; i < n; i++) {
    if (s[i] == '#') {
      c++;
      a[i] = c;
      if (a[i] >= k) {
        cout << "NO\n";
        return 0;
      }
    } else {
      c = 0;
    }
  }
  cout << "YES\n";
  return 0;
}
