#include <bits/stdc++.h>
int main() {
  int n, k, i = 0, fl = 0;
  char s[300005];
  scanf("%d%d%s", &n, &k, s);
  while (s[i + 1] != '\0') {
    int u = (n - 1) < (i + k) ? n - 1 : i + k;
    while (s[u] == '#' && u > i) u--;
    if (u == i) {
      fl = 1;
      break;
    } else
      i = u;
  }
  if (fl)
    printf("NO");
  else
    printf("YES");
  return 0;
}
