#include <bits/stdc++.h>
using namespace std;
const double PI = 3.1415926535;
int n, k, cnt, ans;
string s;
int d[300500];
int main() {
  cin >> n >> k >> s;
  for (int i = 1; i < n; ++i) {
    if (s[i] == '.')
      ans = max(ans, cnt), cnt = 0;
    else
      ++cnt;
  }
  cout << (ans < k ? "YES" : "NO");
  return 0;
}
