#include <bits/stdc++.h>
using namespace std;
const int INF = (int)1e9;
const int mod = (int)1e9 + 7;
const int MAX = (int)2e5 + 5;
int main(void) {
  int n, k;
  scanf("%d %d", &n, &k);
  ;
  string s;
  cin >> s;
  for (int i = 0; i < n - 1; ++i) {
    bool flag = 1;
    for (int j = i + 1; j <= i + k && j < n; ++j) {
      if (s[j] == '.') {
        flag = 0;
        i = j - 1;
        break;
      }
    }
    if (flag) {
      puts("NO");
      return 0;
    }
  }
  puts("YES");
  return 0;
}
