#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const int INF = 0x3f3f3f3f;
int n, k, flag, j;
string s;
int main() {
  cin >> n >> k >> s;
  for (int i = (int)(0); i < (int)(n); i++) {
    if (s[i] == '.' && s[i + 1] == '#') {
      for (j = i + 1; j <= k + i; j++)
        if (s[j] != '#') break;
      if (j == k + i + 1) {
        flag = 1;
        break;
      }
    }
  }
  if (flag)
    cout << "NO" << endl;
  else
    cout << "YES" << endl;
  return 0;
}
