#include <bits/stdc++.h>
using namespace std;
int n, k;
char s[301000];
bool Solve() {
  if (s[0] == '#' || s[n - 1] == '#') return 0;
  int i, j, t;
  i = 0;
  while (i < n - 1) {
    for (j = i + k; j >= i; j--) {
      if (j >= n - 1) return 1;
      if (s[j] == '.') break;
    }
    if (i == j) return 0;
    i = j;
  }
  return 1;
}
int main() {
  while (~scanf("%d%d", &n, &k)) {
    scanf("%s", s);
    if (Solve())
      printf("YES\n");
    else
      printf("NO\n");
  }
  return 0;
}
