#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  int max;
  int count;
  int j, i;
  char a[350000];
  scanf("%d%d", &n, &k);
  max = -1;
  getchar();
  for (i = 0; i < n; i++) {
    scanf("%c", &a[i]);
  }
  for (i = 0; i < n; i++) {
    count = 0;
    if (a[i] == '#') {
      for (j = i; a[j] != '.'; j++) {
        count++;
      }
      i = j;
    }
    if (count >= max) max = count;
  }
  if (max >= k || a[n - 1] == '#')
    printf("NO\n");
  else
    printf("YES\n");
  return 0;
}
