#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, K;
  cin >> N >> K;
  string S;
  cin >> S;
  int Pos = 0;
  while (1) {
    bool Yes = 0;
    for (int i = 1; i <= K; i++) {
      if (S[Pos + i] == '.') {
        Yes = 1;
        Pos += i;
      }
      if (Yes) break;
    }
    if (!Yes) {
      cout << "NO";
      return 0;
    }
    if (Pos + 1 >= S.length()) {
      cout << "YES";
      return 0;
    }
  }
  return 0;
}
