#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};
int n, k;
string s;
int main() {
  cin >> n >> k;
  cin >> s;
  int sum = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] == '#') sum++;
    if (sum >= k) {
      puts("NO");
      return 0;
    }
    if (s[i] == '.') sum = 0;
  }
  puts("YES");
  return 0;
}
