#include <bits/stdc++.h>
using namespace std;
string input;
int main() {
  int n, k;
  while (cin >> n >> k) {
    bool ok = true;
    cin >> input;
    int i = 0, j, l = input.length(), count = 0;
    while (i < l && input[i] == '.') i++;
    while (i < l) {
      while (i < l && input[i] == '#') {
        i++;
        count++;
      }
      if (k > count) {
        while (i < l && input[i] == '.') i++;
        count = 0;
      } else {
        ok = false;
        break;
      }
    }
    if (ok == true)
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
  return 0;
}
