#include <bits/stdc++.h>
using namespace std;
const double pi = 2 * acos(0.0);
const int OO = 0x3f3f3f3f;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, k, cnt = 0;
  cin >> n >> k;
  char c;
  while (n--) {
    cin >> c;
    cnt = (c == '.' ? 0 : cnt + 1);
    if (cnt == k) return cout << "NO", 0;
  }
  cout << "YES";
  return 0;
}
