#include <bits/stdc++.h>
char s[300005];
int main() {
  int n, k;
  scanf("%d%d", &n, &k);
  scanf("%s", s);
  int flag = 1;
  int pos = 0;
  int temp;
  for (int i = 1; i < n; i++) {
    if (s[i] == '.') {
      temp = i - pos;
      pos = i;
      if (temp > k) {
        flag = 0;
        break;
      }
    }
  }
  if (flag) {
    printf("YES\n");
  } else
    printf("NO\n");
}
