#include <bits/stdc++.h>
using namespace std;
int n, k, cnt;
char now;
int main() {
  scanf("%d %d\n", &n, &k);
  for (int i = 0; i < n; i++) {
    scanf("%c", &now);
    if (now == '#') cnt++;
    if (cnt == k) {
      puts("NO");
      return 0;
    }
    if (now == '.') cnt = 0;
  }
  puts("YES");
  return 0;
}
