#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, ma = 0, l, i;
  scanf("%d%d", &n, &m);
  string a;
  cin >> a;
  if (a[0] == '#' || a[a.size() - 1] == '#')
    printf("NO\n");
  else {
    l = 0;
    for (i = 0; i < a.size(); i++)
      if (a[i] == '.') {
        if (l > ma) ma = l;
        l = 0;
      } else
        l++;
    if (ma < m)
      printf("YES\n");
    else
      printf("NO\n");
  }
  return 0;
}
